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Ruby Go
1
Print a literal string on standard output
puts 'Hello World'
fmt.Println("Hello World")
Alternative implementation:
package main
func main(){print("Hello World")}
2
Loop to execute some code a constant number of times
10.times do
  puts "Hello"
end
Alternative implementation:
10.times { puts 'Hello' }
Alternative implementation:
puts "Hello\n" * 10
for i := 0; i < 10; i++ {
	fmt.Println("Hello")
}
Alternative implementation:
fmt.Println(strings.Repeat("Hello\n", 10))
3
Like a function which doesn't return any value, thus has only side effects (e.g. Print to standard output)
def finish( name )
  puts "My job here is done. Goodbye #{name}"
end
func finish(name string) {
  fmt.Println("My job here is done. Good bye " + name)
}
Alternative implementation:
finish := func(name string) {
	fmt.Println("My job here is done. Good bye " + name)
}
4
Create a function which returns the square of an integer
def square(x)
  x*x
end
Alternative implementation:
def square(x) = x*x
func square(x int) int {
  return x*x
}
5
Declare a container type for two floating-point numbers x and y
Point = Struct.new(:x, :y)
type Point struct {
    x, y float64
}
6
Do something with each item x of an array-like collection items, regardless indexes.
items.each{|x| do_something( x )}
Alternative implementation:
items.each do |x|
  do_something( x )
end
for _, x := range items {
    doSomething(x)
}
7
Print each index i with its value x from an array-like collection items
items.each_with_index do |x, i| 
  puts "Item #{i} = #{x}"
end
Alternative implementation:
items.each_index{|i| puts "Item %d = %s" % [i, items[i]]}
for i, x := range items {
    fmt.Printf("Item %d = %v \n", i, x)
}
8
Create a new map object x, and provide some (key, value) pairs as initial content.
x = {one: 1, two: 2}
x := map[string]int {"one": 1, "two": 2}
9
The structure must be recursive because left child and right child are binary trees too. A node has access to children nodes, but not to its parent.
Node = Struct.new(:left, :right, :value)
parent = Node.new(Node.new, Node.new)
type BinTree struct {
	Value valueType
	Left *BinTree
	Right *BinTree
}
10
Generate a random permutation of the elements of list x
x.shuffle
Alternative implementation:
shuffled_list = x.shuffle
for i := range x {
	j := rand.Intn(i + 1)
	x[i], x[j] = x[j], x[i]
}
Alternative implementation:
y := make([]T, len(x))
perm := rand.Perm(len(x))
for i, v := range perm {
	y[v] = x[i]
}
Alternative implementation:
rand.Shuffle(len(x), func(i, j int) {
	x[i], x[j] = x[j], x[i]
})
Alternative implementation:
for i := len(x) - 1; i > 0; i-- {
	j := rand.Intn(i + 1)
	x[i], x[j] = x[j], x[i]
}
11
The list x must be non-empty.
x.sample
x[rand.Intn(len(x))]
Alternative implementation:
func pickT(x []T) T {
	return x[rand.Intn(len(x))]
}
12
Check if the list contains the value x.
list is an iterable finite container.
list.include? x
func Contains(list []T, x T) bool {
	for _, item := range list {
		if item == x {
			return true
		}
	}
	return false
}
13
Access each key k with its value x from an associative array mymap, and print them.
mymap.each {|k, x| puts "Key= #{k}  Value=#{x}"}
for k, x := range mymap {
  fmt.Println("Key =", k, ", Value =", x)
}
14
Pick a random number greater than or equals to a, strictly inferior to b. Precondition : a < b.
rand(a...b)
func pick(a, b  float64)  float64 {
	return a + (rand.Float64() * (b-a))
}
15
Pick a random integer greater than or equals to a, inferior or equals to b. Precondition : a < b.
rand(a..b)
func pick(a,b int) int {
	return a + rand.Intn(b-a+1)
}
16
Call a function f on every node of binary tree bt, in depth-first infix order
def dfs(f, bt)
  dfs(f, bt.left) if bt.left
  f.(bt)
  dfs(f, bt.right) if bt.right
end
func (bt *BinTree) Dfs(f func(*BinTree)) {
	if bt == nil {
		return
	}
	bt.Left.Dfs(f)
	f(bt)
	bt.Right.Dfs(f)
}
17
The structure must be recursive. A node may have zero or more children. A node has access to its children nodes, but not to its parent.
Node = Struct.new(:children)
parent = Node.new([])
parent.children << Node.new([])
type Tree struct {
	Key keyType
	Deco valueType
	Children []*Tree
}
18
Call a function f on every node of a tree, in depth-first prefix order
def dfs(f, node)
  f.(node)
  node.children.each do |child|
    dfs(f, child)
  end
end
func (t *Tree) Dfs(f func(*Tree)) {
	if t == nil {
		return
	}
	f(t)
	for _, child := range t.Children {
		child.Dfs(f)
	}
}
19
Reverse the order of the elements of list x.
This may reverse "in-place" and destroy the original ordering.
x.reverse!
for i, j := 0, len(x)-1; i < j; i, j = i+1, j-1 {
	x[i], x[j] = x[j], x[i]
}
20
Implement a function search which looks for item x in a 2D matrix m.
Return indices i, j of the matching cell.
Think of the most idiomatic way in the language to return the two values at the same time.
def search(m, x)
  m.each_with_index do |row, i|
    row.each_with_index do |value, j|
      return i, j if value == x
    end
  end
  nil
end
func search(m [][]int, x int) (bool, int, int) {
	for i := range m {
		for j, v := range m[i] {
			if v == x {
				return true, i, j
			}
		}
	}
	return false, 0, 0
}
21
Swap the values of the variables a and b
a, b = b, a
a, b = b, a
22
Extract the integer value i from its string representation s (in radix 10)
i = s.to_i
Alternative implementation:
contrato_nf['items']['issueDate'] = data
i, err  := strconv.Atoi(s) 
Alternative implementation:
i, err := strconv.ParseInt(s, 10, 0)
23
Given a real number x, create its string representation s with 2 decimal digits following the dot.
s = "%.2f" % x
s := fmt.Sprintf("%.2f", x)
24
Declare a new string s and initialize it with the literal value "ネコ" (which means "cat" in japanese)
s = "ネコ"
s := "ネコ"
25
Share the string value "Alan" with an existing running process which will then display "Hello, Alan"
queue = Queue.new
thread = Thread.new do
  puts queue.pop
end
queue << "Alan"
thread.join
go func() {
	v := <-ch
	fmt.Printf("Hello, %v\n", v)
}()

ch <- "Alan"
26
Declare and initialize a matrix x having m rows and n columns, containing real numbers.
x = Array.new(m) { Array.new(n) }
const m, n = 3, 4
var x [m][n]float64
Alternative implementation:
func make2D(m, n int) [][]float64 {
	buf := make([]float64, m*n)

	x := make([][]float64, m)
	for i := range x {
		x[i] = buf[:n:n]
		buf = buf[n:]
	}
	return x
}
27
Declare and initialize a 3D array x, having dimensions boundaries m, n, p, and containing real numbers.
x = Array.new(m) { Array.new(n) { Array.new(p) } }
const m, n, p = 2, 2, 3
var x [m][n][p]float64
Alternative implementation:
func make3D(m, n, p int) [][][]float64 {
	buf := make([]float64, m*n*p)

	x := make([][][]float64, m)
	for i := range x {
		x[i] = make([][]float64, n)
		for j := range x[i] {
			x[i][j] = buf[:p:p]
			buf = buf[p:]
		}
	}
	return x
}
28
Sort the elements of the list (or array-like collection) items in ascending order of x.p, where p is a field of the type Item of the objects in items.
items.sort_by(&:p)
type ItemPSorter []Item
func (s ItemPSorter) Len() int{ return len(s) }
func (s ItemPSorter) Less(i,j int) bool{ return s[i].p<s[j].p }
func (s ItemPSorter) Swap(i,j int) { s[i],s[j] = s[j],s[i] }

func sortItems(items []Item){
	sorter := ItemPSorter(items)
	sort.Sort(sorter)
}
Alternative implementation:
less := func(i, j int) bool {
	return items[i].p < items[j].p
}
sort.Slice(items, less)
29
Remove i-th item from list items.
This will alter the original list or return a new list, depending on which is more idiomatic.
Note that in most languages, the smallest valid value for i is 0.
items.delete_at(i) 
items = append(items[:i], items[i+1:]...)
Alternative implementation:
copy(items[i:], items[i+1:])
items[len(items)-1] = nil
items = items[:len(items)-1]
30
Launch the concurrent execution of procedure f with parameter i from 1 to 1000.
Tasks are independent and f(i) doesn't return any value.
Tasks need not run all at the same time, so you may use a pool.
threads = 1000.times.map do |i|
  Thread.new { f(i) }
end
threads.join
wg := sync.WaitGroup{}
wg.Add(1000)
for i := 1; i <= 1000; i++ {
	go func(j int) {
          f(j)
          wg.Done()
        }(i)
}
wg.Wait()
31
Create the recursive function f which returns the factorial of the non-negative integer i, calculated from f(i-1)
f = Hash.new { |hash, i| hash[i] = i * hash[i -1] }
f[0] = 1
Alternative implementation:
fac = Hash.new {|h, i| h[i] = i * h[i-1] }.tap {|h| h[0] = 1 }
func f(i int) int {
  if i == 0 {
    return 1
  }
  return i * f(i-1)
}
32
Create function exp which calculates (fast) the value x power n.
x and n are non-negative integers.
def exp(x, n)
  x ** n
end
Alternative implementation:
def exp(x, n)
  return 1 if n == 0
  return x if n == 1
  return exp(x*x, n/2) if n.even?
  x * exp(x*x, (n-1)/2)
end
func exp(x, n int) int {
	switch {
	case n == 0:
		return 1
	case n == 1:
		return x
	case n%2 == 0:
		return exp(x*x, n/2)
	default:
		return x * exp(x*x, (n-1)/2)
	}
}
33
Assign to the variable x the new value f(x), making sure that no other thread may modify x between the read and the write.
x = Atomic.new(0)
x.update { |x| f(x) }
var lock sync.RWMutex

lock.Lock()
x = f(x)
lock.Unlock()
34
Declare and initialize a set x containing unique objects of type T.
x = Set.new
x := make(map[T]bool)
Alternative implementation:
x := make(map[T]struct{})
35
Implement a function compose (A -> C) with parameters f (A -> B) and g (B -> C), which returns composition function g ∘ f
def compose(f, g)
  -> x { g.(f.(x)) }
end
func compose(f func(A) B, g func(B) C) func(A) C {
	return func(x A) C {
		return g(f(x))
	}
}
36
Implement a function compose which returns composition function g ∘ f for any functions f and g having exactly 1 parameter.
def compose(f, g)
  -> x { g.(f.(x)) }
end
Alternative implementation:
def compose(f, g)
  f >> g
end
func composeIntFuncs(f func(int) int, g func(int) int) func(int) int {
	return func(x int) int {
		return g(f(x))
	}
}
37
Transform a function that takes multiple arguments into a function for which some of the arguments are preset.
adder = -> a, b { a + b }
add_two = adder.curry.(2)
add_two.(5) # => 7
type PayFactory func(Company, *Employee, *Employee) Payroll

type CustomPayFactory func(*Employee) Payroll

func CurryPayFactory(pf PayFactory,company Company, boss *Employee) CustomPayFactory {
	return func(e *Employee) Payroll {
		return pf(company, boss, e)
	}
}
38
Find substring t consisting in characters i (included) to j (excluded) of string s.
Character indices start at 0 unless specified otherwise.
Make sure that multibyte characters are properly handled.
t = s[i..j-1] 
t := string([]rune(s)[i:j])
39
Set boolean ok to true if string word is contained in string s as a substring, or to false otherwise.
ok = s.include?(word)
ok := strings.Contains(s, word)
40
Declare a Graph data structure in which each Vertex has a collection of its neighbouring vertices.
Vertex = Struct.new(:x, :y, :z)
Graph = Struct.new(:vertex, :neighbours)

v = Vertex.new(1, 2, 3)
neighbours = [ Vertex.new(2, 3, 4), Vertex.new(4, 5, 6) ]
graph = Graph.new(v, neighbours)
type Vertex struct{
	Id int
	Label string
	Neighbours map[*Vertex]bool
}

type Graph []*Vertex
41
Create string t containing the same characters as string s, in reverse order.
Original string s must remain unaltered. Each character must be handled correctly regardless its number of bytes in memory.
t = s.reverse
runes := []rune(s)
for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
   runes[i], runes[j] = runes[j], runes[i]
}
t := string(runes)
42
Print each item v of list a which is not contained in list b.
For this, write an outer loop to iterate on a and an inner loop to iterate on b.
a.each do |v|
  catch :matched do
    b.each do |u|
      throw :matched if v == u
    end
    puts v
  end  
end
mainloop:
	for _, v := range a {
		for _, w := range b {
			if v == w {
				continue mainloop
			}
		}
		fmt.Println(v)
	}
43
Look for a negative value v in 2D integer matrix m. Print it and stop searching.
negative_value = catch :negative do
  matrix.each do |row|
    row.each do |value|
      throw :negative, value if value < 0
    end
  end
end

puts negative_value
mainloop:
	for i, line := range m {
		for _, v := range line {
			if v < 0 {
				fmt.Println(v)
				break mainloop
			}
		}
	}
44
Insert element x at position i in list s. Further elements must be shifted to the right.
s.insert(i, x)
s = append(s, 0)
copy(s[i+1:], s[i:])
s[i] = x
45
Sleep for 5 seconds in current thread, before proceeding with the next instructions.
sleep 5
time.Sleep(5 * time.Second)
46
Create string t consisting of the 5 first characters of string s.
Make sure that multibyte characters are properly handled.
t = s[0, 5]
Alternative implementation:
t = s.slice(0, 5)
Alternative implementation:
t = s.slice(0...5)
t := string([]rune(s)[:5])
47
Create string t consisting in the 5 last characters of string s.
Make sure that multibyte characters are properly handled.
t = s[-5..-1]
Alternative implementation:
t = s[-5..]
t := string([]rune(s)[len([]rune(s))-5:])
48
Assign to variable s a string literal consisting in several lines of text, including newlines.
s = "Spanning
string
works"
s := `Huey
Dewey
Louie`
49
Build list chunks consisting in substrings of input string s, separated by one or more space characters.
chunks = s.split
chunks := strings.Split(s, " ")
Alternative implementation:
chunks := strings.Fields(s)
50
Write a loop that has no end clause.
loop do
  # endless joy
end
for {
	// Do something
}
51
Determine whether the map m contains an entry for the key k
m.include?(k)
Alternative implementation:
m.key?(k)
Alternative implementation:
m.has_key?(k)
_, ok := m[k]
52
Determine whether the map m contains an entry with the value v, for some key.
m.value?(v)
func containsValue(m map[K]T, v T) bool {
	for _, x := range m {
		if x == v {
			return true
		}
	}
	return false
}
53
Concatenate elements of string list x joined by the separator ", " to create a single string y.
y = x.join(", ")
y := strings.Join(x, ", ")
54
Calculate the sum s of the integer list or array x.
s = x.sum
Alternative implementation:
s = x.reduce(:+)
s := 0
for _, v := range x {
	s += v
}
55
Create the string representation s (in radix 10) of the integer value i.
s = i.to_s
s := strconv.Itoa(i)
Alternative implementation:
s := strconv.FormatInt(i, 10)
Alternative implementation:
s := fmt.Sprintf("%d", i)
56
Fork-join : launch the concurrent execution of procedure f with parameter i from 1 to 1000.
Tasks are independent and f(i) doesn't return any value.
Tasks need not run all at the same time, so you may use a pool.
Wait for the completion of the 1000 tasks and then print "Finished".
threads = 1000.times.map do |i|
  Thread.new { f(i) }
end
threads.join
var wg sync.WaitGroup
wg.Add(1000)
for i := 1; i <= 1000; i++ {
	go func(i int) {
		f(i)
		wg.Done()
	}(i)
}
wg.Wait()
fmt.Println("Finished")
57
Create the list y containing the items from the list x that satisfy the predicate p. Respect the original ordering. Don't modify x in-place.
y = x.select(&:p)
y := make([]T, 0, len(x))
for _, v := range x{
	if p(v){
		y = append(y, v)
	}
}
Alternative implementation:
n := 0
for _, v := range x {
	if p(v) {
		n++
	}
}
y := make([]T, 0, n)
for _, v := range x {
	if p(v) {
		y = append(y, v)
	}
}
58
Create string lines from the content of the file with filename f.
lines = File.read(f)
b, err := ioutil.ReadFile(f)
if err != nil {
	// Handle error...
}
lines := string(b)
59
Print the message "x is negative" to standard error (stderr), with integer x value substitution (e.g. "-2 is negative").
warn "#{x} is negative"
$stderr.puts "%d is negative" % x
fmt.Fprintln(os.Stderr, x, "is negative")
60
Assign to x the string value of the first command line parameter, after the program name.
x = ARGV.first
x := os.Args[1]
61
Assign to the variable d the current date/time value, in the most standard type.
d = Time.now
d := time.Now()
62
Set i to the first position of string y inside string x, if exists.

Specify if i should be regarded as a character index or as a byte index.

Explain the behavior when y is not contained in x.
i = x.index(y)
i := strings.Index(x, y)
63
Assign to x2 the value of string x with all occurrences of y replaced by z.
Assume occurrences of y are not overlapping.
x2 = x.gsub(y, z)
x2 := strings.Replace(x, y, z, -1)
64
Assign to x the value 3^247
x = 3 ** 247
x := new(big.Int)
x.Exp(big.NewInt(3), big.NewInt(247), nil)
65
From the real value x in [0,1], create its percentage string representation s with one digit after decimal point. E.g. 0.15625 -> "15.6%"
s = "%.1f%%" % (100 * x)
s := fmt.Sprintf("%.1f%%", 100.0*x)
66
Calculate the result z of x power n, where x is a big integer and n is a positive integer.
z = x ** n
nb := big.NewInt(int64(n))
var z big.Int
z.Exp(x, nb, nil)
67
Calculate binom(n, k) = n! / (k! * (n-k)!). Use an integer type able to handle huge numbers.
def binom(n,k)
  (1+n-k..n).inject(:*)/(1..k).inject(:*)
end
z := new(big.Int)
z.Binomial(n, k)
68
Create an object x to store n bits (n being potentially large).
x = 0
var x *big.Int = new(big.Int)
Alternative implementation:
x := make([]bool, n)
Alternative implementation:
x := make([]uint64, (n+63)/64)
69
Use seed s to initialize a random generator.

If s is constant, the generator output will be the same each time the program runs. If s is based on the current value of the system clock, the generator output will be different each time.
r = Random.new(s)
rand.Seed(s)
Alternative implementation:
r := rand.New(rand.NewSource(s))
70
Get the current datetime and provide it as a seed to a random generator. The generator sequence will be different at each run.
Random.new
rand.Seed(time.Now().UnixNano())
Alternative implementation:
r := rand.New(rand.NewSource(time.Now().UnixNano()))
71
Basic implementation of the Echo program: Print all arguments except the program name, separated by space, followed by newline.
The idiom demonstrates how to skip the first argument if necessary, concatenate arguments as strings, append newline and print it to stdout.
printf("%s\n", ARGV.join(' '))
Alternative implementation:
puts ARGV.join(' ')
func main() {
    fmt.Println(strings.Join(os.Args[1:], " "))
}
73
Create a factory named fact for any sub class of Parent and taking exactly one string str as constructor parameter.
def fact(klass, str)
  klass.new(str) if klass.is_a?(Parent)
end
type ParentFactory func(string) Parent

var fact ParentFactory = func(str string) Parent {
	return Parent{
		name: str,
	}
}
74
Compute the greatest common divisor x of big integers a and b. Use an integer type able to handle huge numbers.
x = a.gcd(b)
x.GCD(nil, nil, a, b)
75
Compute the least common multiple x of big integers a and b. Use an integer type able to handle huge numbers.
x = a.lcm(b)
gcd.GCD(nil, nil, a, b)
x.Div(a, gcd).Mul(x, b)
76
Create the string s of integer x written in base 2.

E.g. 13 -> "1101"
s = x.to_s(2)
s := strconv.FormatInt(x, 2)
Alternative implementation:
s := fmt.Sprintf("%b", x)
77
Declare a complex x and initialize it with value (3i - 2). Then multiply it by i.
x = 3i - 2
x *= 1i
x := 3i - 2
x *= 1i
78
Execute a block once, then execute it again as long as boolean condition c is true.
begin
  # code
end while c
for{
   someThing()
   someOtherThing()
   if !c {
     break
   }
}
Alternative implementation:
for done := false; !done; {
	someThing()
	someOtherThing()
	done = !c()
}
79
Declare the floating point number y and initialize it with the value of the integer x .
y = x.to_f
y := float64(x)
80
Declare integer y and initialize it with the value of floating point number x . Ignore non-integer digits of x .
Make sure to truncate towards zero: a negative x must yield the closest greater integer (not lesser).
y = x.to_i
y := int(x)
81
Declare integer y and initialize it with the rounded value of floating point number x .
Ties (when the fractional part of x is exactly .5) must be rounded up (to positive infinity).
y = (x + 1/2r).floor
y := int(math.Floor(x + 0.5))
82
Find how many times string s contains substring t.
Specify if overlapping occurrences are counted.
s.scan(t).size
x := strings.Count(s, t)
83
Declare regular expression r matching strings "http", "htttp", "httttp", etc.
r = /htt+p/
r := regexp.MustCompile("htt+p")
84
Count number c of 1s in the integer i in base 2.

E.g. i=6 → c=2
c = i.digits(2).count(1)
func PopCountUInt64(i uint64) (c int) {
	i -= (i >> 1) & 0x5555555555555555
	i = (i>>2)&0x3333333333333333 + i&0x3333333333333333
	i += i >> 4
	i &= 0x0f0f0f0f0f0f0f0f
	i *= 0x0101010101010101
	return int(i >> 56)
}

func PopCountUInt32(i uint32) (n int) {
	i -= (i >> 1) & 0x55555555
	i = (i>>2)&0x33333333 + i&0x33333333
	i += i >> 4
	i &= 0x0f0f0f0f
	i *= 0x01010101
	return int(i >> 24)
}
Alternative implementation:
c := bits.OnesCount(i)
85
Write boolean function addingWillOverflow which takes two integers x, y and return true if (x+y) overflows.

An overflow may be above the max positive value, or below the min negative value.
def addingWillOverflow(x,y)
  false
end
func addingWillOverflow(x int, y int) bool {
	if x > 0 {
		return y > math.MaxInt-x
	}
	return y < math.MinInt-x
}
86
Write boolean function multiplyWillOverflow which takes two integers x, y and return true if (x*y) overflows.

An overflow may be above the max positive value, or below the min negative value.
def multiplyWillOverflow(x,y)
  false
end
func multiplyWillOverflow(x, y uint64) bool {
   if x <= 1 || y <= 1 {
     return false
   }
   d := x * y
   return d/y != x
}
87
Exit immediately.
If some extra cleanup work is executed by the program runtime (not by the OS itself), describe it.
exit
os.Exit(0)
88
Create a new bytes buffer buf of size 1,000,000.
(' ' * 1_000_000).bytes.to_a
buf := make([]byte, 1_000_000)
89
You've detected that the integer value of argument x passed to the current function is invalid. Write the idiomatic way to abort the function execution and signal the problem.
raise ArgumentError, "invalid value #{x}."
return nil, fmt.Errorf("invalid value for x: %v", x)
90
Expose a read-only integer x to the outside world while being writable inside a structure or a class Foo.
class Foo

  def initialize
    @x = rand(10)
  end

  def x
    @x
  end

end

type Foo struct {
	x int
}

func (f *Foo) X() int {
	return f.x
}
91
Read from the file data.json and write its content into the object x.
Assume the JSON data is suitable for the type of x.
x = JSON.parse(File.read('data.json'))
buffer, err := ioutil.ReadFile("data.json")
if err != nil {
	return err
}
err = json.Unmarshal(buffer, &x)
if err != nil {
	return err
}
Alternative implementation:
r, err := os.Open(filename)
if err != nil {
	return err
}
decoder := json.NewDecoder(r)
err = decoder.Decode(&x)
if err != nil {
	return err
}
92
Write the contents of the object x into the file data.json.
x = {:hello => "goodbye"}

File.open("data.json", "w") do |f|
  f.puts(x.to_json)
end
buffer, err := json.MarshalIndent(x, "", "  ")
if err != nil {
	return err
}
err = ioutil.WriteFile("data.json", buffer, 0644)
93
Implement procedure control which receives one parameter f, and runs f.
def control
    yield
end
func control(f func()) {
	f()
}
94
Print the name of the type of x. Explain if it is a static type or dynamic type.

This may not make sense in all languages.
puts x.class
fmt.Println(reflect.TypeOf(x))
Alternative implementation:
fmt.Printf("%T", x)
95
Assign to variable x the length (number of bytes) of the local file at path.
x = File.size(path)
info, err := os.Stat(path)
if err != nil {
	return err
}
x := info.Size()
96
Set boolean b to true if string s starts with prefix prefix, false otherwise.
b = s.start_with?(prefix)
b := strings.HasPrefix(s, prefix)
97
Set boolean b to true if string s ends with string suffix, false otherwise.
b = s.end_with?(suffix)
b := strings.HasSuffix(s, suffix)
98
Convert a timestamp ts (number of seconds in epoch-time) to a date with time d. E.g. 0 -> 1970-01-01 00:00:00
d = DateTime.strptime(ts, '%s')
d := time.Unix(ts, 0)
99
Assign to the string x the value of the fields (year, month, day) of the date d, in format YYYY-MM-DD.
d = Date.today
x = d.to_s
x := d.Format("2006-01-02")
100
Sort elements of array-like collection items, using a comparator c.
items.sort!{|a,b| a-b }
Alternative implementation:
items.sort!(&c)
type ItemCSorter []Item
func (s ItemCSorter) Len() int           { return len(s) }
func (s ItemCSorter) Less(i, j int) bool { return c(s[i], s[j]) }
func (s ItemCSorter) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

func sortItems(items []Item) {
	sorter := ItemCSorter(items)
	sort.Sort(sorter)
}
Alternative implementation:
type ItemsSorter struct {
	items []Item
	c     func(x, y Item) bool
}

func (s ItemsSorter) Len() int           { return len(s.items) }
func (s ItemsSorter) Less(i, j int) bool { return s.c(s.items[i], s.items[j]) }
func (s ItemsSorter) Swap(i, j int)      { s.items[i], s.items[j] = s.items[j], s.items[i] }

func sortItems(items []Item, c func(x, y Item) bool) {
	sorter := ItemsSorter{
		items,
		c,
	}
	sort.Sort(sorter)
}
Alternative implementation:
sort.Slice(items, func(i, j int) bool {
	return c(items[i], items[j])
})
101
Make an HTTP request with method GET to the URL u, then store the body of the response in the string s.
u = URI("http://example.com/index.html")
s = Net::HTTP.get_response(u).body
res, err := http.Get(u)
if err != nil {
	return err
}
buffer, err := ioutil.ReadAll(res.Body)
res.Body.Close()
if err != nil {
	return err
}
s := string(buffer)
102
Make an HTTP request with method GET to URL u, then store the body of the response in file result.txt. Try to save the data as it arrives if possible, without having all its content in memory at once.
u = URI('http://example.com/large_file')

Net::HTTP.start(u.host, u.port) do |http|
  request = Net::HTTP::Get.new(u)
  http.request(request) do |response|
    open('result.txt', 'w') do |file|
      response.read_body do |chunk|
        file.write(chunk)
      end
    end
  end
end
resp, err := http.Get(u)
if err != nil {
	return err
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
	return fmt.Errorf("Status: %v", resp.Status)
}
out, err := os.Create("result.txt")
if err != nil {
	return err
}
defer out.Close()
_, err = io.Copy(out, resp.Body)
if err != nil {
	return err
}
103
Read from the file data.xml and write its contents into the object x.
Assume the XML data is suitable for the type of x.
buffer, err := ioutil.ReadFile("data.xml")
if err != nil {
	return err
}
err = xml.Unmarshal(buffer, &x)
if err != nil {
	return err
}
104
Write the contents of the object x into the file data.xml.
class Person
  include XML::Mapping
  attr_accessor :name, :surname, :age, :children

  text_node :from, "@from"
  text_node :name, "Name"
  text_node :surname, "Surname"

  def initialize(name, surname, ..)
    # ...
  end
end

x = Person.new(..)
x.save_to_xml.write($stdout,2) # nicely prints
x.save_to_file('data.xml')
buffer, err := xml.MarshalIndent(x, "", "  ")
if err != nil {
	return err
}
err = ioutil.WriteFile("data.xml", buffer, 0644)
105
Assign to the string s the name of the currently executing program (but not its full path).
s = __FILE__
Alternative implementation:
s = $0
path := os.Args[0]
s = filepath.Base(path)
Alternative implementation:
path, err := os.Executable()
if err != nil {
  panic(err)
}
s = filepath.Base(path)
106
Assign to string dir the path of the working directory.
(This is not necessarily the folder containing the executable itself)
dir = Dir.pwd
dir, err := os.Getwd()
107
Assign to string dir the path of the folder containing the currently running executable.
(This is not necessarily the working directory, though.)
dir = __dir__
programPath := os.Args[0]
absolutePath, err := filepath.Abs(programPath)
if err != nil {
	return err
}
dir := filepath.Dir(absolutePath)
108
Print the value of variable x, but only if x has been declared in this program.
This makes sense in some languages, not all of them. (Null values are not the point, rather the very existence of the variable.)
puts x if defined?(x)
109
Set n to the number of bytes of a variable t (of type T).
n = ObjectSpace.memsize_of(t)
var t T
tType := reflect.TypeOf(t)
n := tType.Size()
110
Set the boolean blank to true if the string s is empty, or null, or contains only whitespace ; false otherwise.
blank = s.strip.empty?
Alternative implementation:
blank = s.nil? || s.blank?
blank := strings.TrimSpace(s) == ""
111
From current process, run program x with command-line parameters "a", "b".
`x a b`
err := exec.Command("x", "a", "b").Run()
112
Print each key k with its value x from an associative array mymap, in ascending order of k.
my_map.sort.each{|k,x| puts "#{k}: #{x}"}
keys := make([]string, 0, len(mymap))
for k := range mymap {
	keys = append(keys, k)
}
sort.Strings(keys)

for _, k := range keys {
	x := mymap[k]
	fmt.Println("Key =", k, ", Value =", x)
}
113
Print each key k with its value x from an associative array mymap, in ascending order of x.
Note that multiple entries may exist for the same value x.
h.sort_by{|k,x| x}.each{|k,x| puts "#{k}: #{x}"}
type entry struct {
	key   string
	value int
}

type entries []entry
func (list entries) Len() int { return len(list) }
func (list entries) Less(i, j int) bool { return list[i].value < list[j].value }
func (list entries) Swap(i, j int) { list[i], list[j] = list[j], list[i] }

entries := make(entries, 0, len(mymap))
for k, x := range mymap {
	entries = append(entries, entry{key: k, values: x})
}
sort.Sort(entries)

for _, e := range entries {
	fmt.Println("Key =", e.key, ", Value =", e.value)
}
Alternative implementation:
type entry struct {
	key   string
	value int
}

entries := make([]entry, 0, len(mymap))
for k, x := range mymap {
	entries = append(entries, entry{key: k, value: x})
}
sort.Slice(entries, func(i, j int) bool {
	return entries[i].value < entries[j].value
})

for _, e := range entries {
	fmt.Println("Key =", e.key, ", Value =", e.value)
}
114
Set boolean b to true if objects x and y contain the same values, recursively comparing all referenced elements in x and y.
Tell if the code correctly handles recursive types.
b = x == y
b := reflect.DeepEqual(x, y)
115
Set boolean b to true if date d1 is strictly before date d2 ; false otherwise.
b = d1 < d2
b := d1.Before(d2)
116
Remove all occurrences of string w from string s1, and store the result in s2.
s2 = s1.gsub(w, "")
s2 := strings.Replace(s1, w, "", -1)
Alternative implementation:
s2 := strings.ReplaceAll(s1, w, "")
117
Set n to the number of elements of the list x.
n = x.length
n := len(x)
118
Create the set y from the list x.
x may contain duplicates. y is unordered and has no repeated values.
y = x.to_set
y := make(map[T]struct{}, len(x))
for _, v := range x {
	y[v] = struct{}{}
}
119
Remove duplicates from the list x.
Explain if the original order is preserved.
x.uniq!
y := make(map[T]struct{}, len(x))
for _, v := range x {
	y[v] = struct{}{}
}
x2 := make([]T, 0, len(y))
for _, v := range x {
	if _, ok := y[v]; ok {
		x2 = append(x2, v)
		delete(y, v)
	}
}
x = x2
Alternative implementation:
seen := make(map[T]bool)
j := 0
for _, v := range x {
	if !seen[v] {
		x[j] = v
		j++
		seen[v] = true
	}
}
x = x[:j]
Alternative implementation:
seen := make(map[T]bool)
j := 0
for _, v := range x {
	if !seen[v] {
		x[j] = v
		j++
		seen[v] = true
	}
}
for i := j; i < len(x); i++ {
	x[i] = nil
}
x = x[:j]
120
Read an integer value from the standard input into the variable n
n = $stdin.gets.to_i
_, err := fmt.Scan(&n)
Alternative implementation:
_, err := fmt.Scanf("%d", &n)
121
Listen UDP traffic on port p and read 1024 bytes into buffer b.
require 'socket'

p = 4913
u1 = UDPSocket.new
u1.bind("127.0.0.1", p)
u1.send "message-to-self", 0, "127.0.0.1", p

b = u1.recvfrom(1024).first
ServerAddr,err := net.ResolveUDPAddr("udp",p)
if err != nil {
	return err
}
ServerConn, err := net.ListenUDP("udp", ServerAddr)
if err != nil {
	return err
}
defer ServerConn.Close()
n,addr,err := ServerConn.ReadFromUDP(b[:1024])
if err != nil {
	return err
}
if n<1024 {
	return fmt.Errorf("Only %d bytes could be read.", n)
}
122
Create an enumerated type Suit with 4 possible values SPADES, HEARTS, DIAMONDS, CLUBS.
class Colors
  include Ruby::Enum

  define :SPADES, "spades"
  define :HEARTS, "hearts"
  define :DIAMONDS, "diamonds"
  define :CLUBS, "clubs"
end
type Suit int

const (
  Spades Suit = iota
  Hearts
  Diamonds
  Clubs
)
123
Verify that predicate isConsistent returns true, otherwise report assertion violation.
Explain if the assertion is executed even in production environment or not.
raise unless isConsistent
if !isConsistent() {
	panic("State consistency violated")
}
124
Write the function binarySearch which returns the index of an element having the value x in the sorted array a, or -1 if no such element exists.
def binary_search(a, el)
  a.bsearch_index{|x| x == el} || -1
end
func binarySearch(a []T, x T) int {
	imin, imax := 0, len(a)-1
	for imin <= imax {
		imid := imin + (imax-imin) / 2
		switch {
		case a[imid] == x:
			return imid
		case a[imid] < x:
			imin = imid + 1
		default:
			imax = imid - 1
		}
	}
	return -1
}
Alternative implementation:
func binarySearch(a []int, x int) int {
	i := sort.SearchInts(a, x)
	if i < len(a) && a[i] == x {
		return i
	}
	return -1
}
Alternative implementation:
func binarySearch(a []T, x T) int {
	f := func(i int) bool { return a[i] >= x }
	i := sort.Search(len(a), f)
	if i < len(a) && a[i] == x {
		return i
	}
	return -1
}
125
measure the duration t, in nanoseconds, of a call to the function foo. Print this duration.
t1 = Time.now
foo
p (Time.now - t1)*1000000
t1 := time.Now()
foo()
t := time.Since(t1)
ns := int64(t / time.Nanosecond)
fmt.Printf("%dns\n", ns)
Alternative implementation:
t1 := time.Now()
foo()
t := time.Since(t1)
ns := t.Nanoseconds()
fmt.Printf("%dns\n", ns)
126
Write a function foo that returns a string and a boolean value.
def foo
  string, boolean  = "bar", false
  [string, boolean]
end
func foo() (string, bool) {
	return "Too good to be", true
}
127
Import the source code for the function foo body from a file "foobody.txt".
def foo
  eval File.read "foobody.txt"
end
128
Call a function f on every node of a tree, in breadth-first prefix order
class Tree
  attr_accessor :value, :children

  def initialize(value)
    @value = value
    @children = []
  end

  def traverse_breadth_first(f)
    queue = []
    queue.unshift(self)
    while !(queue.empty?)
      node = queue.pop
      method(f).call(node.value)
      node.children.each { |child| queue.unshift(child) }
    end
  end
end
func (root *Tree) Bfs(f func(*Tree)) {
	if root == nil {
		return
	}
	queue := []*Tree{root}
	for len(queue) > 0 {
		t := queue[0]
		queue = queue[1:]
		f(t)
		queue = append(queue, t.Children...)
	}
}
129
Call the function f on every vertex accessible from the vertex start, in breadth-first prefix order
func (start *Vertex) Bfs(f func(*Vertex)) {
	queue := []*Vertex{start}
	seen := map[*Vertex]bool{start: true}
	for len(queue) > 0 {
		v := queue[0]
		queue = queue[1:]
		f(v)
		for next, isEdge := range v.Neighbours {
			if isEdge && !seen[next] {
				queue = append(queue, next)
				seen[next] = true
			}
		}
	}
}
130
Call th function f on every vertex accessible from the vertex v, in depth-first prefix order
func (v *Vertex) Dfs(f func(*Vertex), seen map[*Vertex]bool) {
	seen[v] = true
	f(v)
	for next, isEdge := range v.Neighbours {
		if isEdge && !seen[next] {
			next.Dfs(f, seen)
		}
	}
}
131
Execute f1 if condition c1 is true, or else f2 if condition c2 is true, or else f3 if condition c3 is true.
Don't evaluate a condition when a previous condition was true.
case
  when c1
    f1
  when c2
    f2
  when c3
    f3
end
switch {
case c1:
	f1()
case c2:
	f2()
case c3:
	f3()
}
132
Run procedure f, and return the duration of the execution of f.
def clock 
  t = Time.now
  yield
  Time.now - t
end

clock{ f }
func clock(f func()) time.Duration {
	t := time.Now()
	f()
	return time.Since(t)
}
133
Set boolean ok to true if string word is contained in string s as a substring, even if the case doesn't match, or to false otherwise.
ok = s.match?( /#{word}/i )
lowerS, lowerWord := strings.ToLower(s), strings.ToLower(word)
ok := strings.Contains(lowerS, lowerWord)
134
Declare and initialize a new list items, containing 3 elements a, b, c.
items = [a, b, c]
items := []T{a, b, c}
135
Remove at most 1 item from list items, having value x.
This will alter the original list or return a new list, depending on which is more idiomatic.
If there are several occurrences of x in items, remove only one of them. If x is absent, keep items unchanged.
i = items.index(x)
items.delete_at(i) unless i.nil?
for i, y := range items {
	if y == x {
		items = append(items[:i], items[i+1:]...)
		break
	}
}
Alternative implementation:
for i, y := range items {
	if y == x {
		copy(items[i:], items[i+1:])
		items[len(items)-1] = nil
		items = items[:len(items)-1]
		break
	}
}
136
Remove all occurrences of value x from list items.
This will alter the original list or return a new list, depending on which is more idiomatic.
items.delete(x)
items2 := make([]T, 0, len(items))
for _, v := range items {
	if v != x {
		items2 = append(items2, v)
	}
}
Alternative implementation:
j := 0
for i, v := range items {
	if v != x {
		items[j] = items[i]
		j++
	}
}
items = items[:j]
Alternative implementation:
j := 0
for i, v := range items {
	if v != x {
		items[j] = items[i]
		j++
	}
}
for k := j; k < len(items); k++ {
	items[k] = nil
}
items = items[:j]
137
Set the boolean b to true if the string s contains only characters in the range '0'..'9', false otherwise.
b = s.count("^0-9").zero?
b := true
for _, c := range s {
	if c < '0' || c > '9' {
		b = false
		break
	}
}
Alternative implementation:
isNotDigit := func(c rune) bool { return c < '0' || c > '9' }
b := strings.IndexFunc(s, isNotDigit) == -1
138
Create a new temporary file on the filesystem.
file = Tempfile.new('foo') 
tmpfile, err := ioutil.TempFile("", "")
139
Create a new temporary folder on filesystem, for writing.
td = Dir.mktmpdir
dir, err := ioutil.TempDir("", "")
140
Delete from map m the entry having key k.

Explain what happens if k is not an existing key in m.
m.delete(k)
delete(m, k)
141
Iterate in sequence over the elements of the list items1 then items2. For each iteration print the element.
[items1, items2].each{|ar| ar.each{|item| p item }}
Alternative implementation:
items1.chain(items2).each{|item| puts item}
for _, v := range items1 {
	fmt.Println(v)
}
for _, v := range items2 {
	fmt.Println(v)
}
142
Assign to string s the hexadecimal representation (base 16) of integer x.

E.g. 999 -> "3e7"
s = x.to_s(16)
s := strconv.FormatInt(x, 16)
Alternative implementation:
s := fmt.Sprintf("%x", x)
143
Iterate alternatively over the elements of the list items1 and items2. For each iteration, print the element.

Explain what happens if items1 and items2 have different size.
items1.zip(items2){|pair| puts pair}
for i := 0; i < len(items1) || i < len(items2); i++ {
	if i < len(items1) {
		fmt.Println(items1[i])
	}
	if i < len(items2) {
		fmt.Println(items2[i])
	}
}
144
Set boolean b to true if file at path fp exists on filesystem; false otherwise.

Beware that you should never do this and then in the next instruction assume the result is still valid, this is a race condition on any multitasking OS.
b = File.exist?(fp)
_, err := os.Stat(fp)
b := !os.IsNotExist(err)
145
Print message msg, prepended by current date and time.

Explain what behavior is idiomatic: to stdout or stderr, and what the date format is.
logger = Logger.new('logfile.log') # or STDOUT or STDERR
logger.info(msg)
log.Println(msg)
146
Extract floating point value f from its string representation s
f = s.to_f
f, err := strconv.ParseFloat(s, 64)
147
Create string t from string s, keeping only ASCII characters
t = s.gsub(/[^[:ascii:]]/, "")
Alternative implementation:
t = s.gsub(/[[:^ascii:]]/, "")
re := regexp.MustCompile("[[:^ascii:]]")
t := re.ReplaceAllLiteralString(s, "")
Alternative implementation:
t := strings.Map(func(r rune) rune {
	if r > unicode.MaxASCII {
		return -1
	}
	return r
}, s)
148
Read a list of integer numbers from the standard input, until EOF.
STDIN.read.split.map(&:to_i)
var ints []int
s := bufio.NewScanner(os.Stdin)
s.Split(bufio.ScanWords)
for s.Scan() {
	i, err := strconv.Atoi(s.Text())
	if err == nil {
		ints = append(ints, i)
	}
}
if err := s.Err(); err != nil {
	return err
}
149
As an exception, this content is not under license CC BY-SA 3.0 like the rest of this website.
 
150
Remove last character from string p, if this character is a slash /.
p.chomp!("/")
Alternative implementation:
p = p.chomp("/")
p = strings.TrimSuffix(p, "/")
151
Remove last character from string p, if this character is the file path separator of current platform.

Note that this also transforms unix root path "/" into the empty string!
p.chomp!("/")
sep := fmt.Sprintf("%c", os.PathSeparator)
p = strings.TrimSuffix(p, sep)
Alternative implementation:
sep := fmt.Sprintf("%c", filepath.Separator)
p = strings.TrimSuffix(p, sep)
152
Create string s containing only the character c.
s = ?c
s := fmt.Sprintf("%c", c)
153
Create the string t as the concatenation of the string s and the integer i.
t = s + i.to_s
t := fmt.Sprintf("%s%d", s, i)
Alternative implementation:
t := s + strconv.Itoa(i)
154
Find color c, the average between colors c1, c2.

c, c1, c2 are strings of hex color codes: 7 chars, beginning with a number sign # .
Assume linear computations, ignore gamma corrections.
rgbs = c1[1..-1].scan(/../), c2[1..-1].scan(/../)
c = "#%02X%02X%02X" % rgbs.transpose.map{|h1, h2| (h1.hex + h2.hex)/2 }
r1, _ := strconv.ParseInt(c1[1:3], 16, 0)
r2, _ := strconv.ParseInt(c2[1:3], 16, 0)
r := (r1 + r2) / 2

g1, _ := strconv.ParseInt(c1[3:5], 16, 0)
g2, _ := strconv.ParseInt(c2[3:5], 16, 0)
g := (g1 + g2) / 2

b1, _ := strconv.ParseInt(c1[5:7], 16, 0)
b2, _ := strconv.ParseInt(c2[5:7], 16, 0)
b := (b1 + b2) / 2

c := fmt.Sprintf("#%02X%02X%02X", r, g, b)
Alternative implementation:
var buf [7]byte
buf[0] = '#'
for i := 0; i < 3; i++ {
	sub1 := c1[1+2*i : 3+2*i]
	sub2 := c2[1+2*i : 3+2*i]
	v1, _ := strconv.ParseInt(sub1, 16, 0)
	v2, _ := strconv.ParseInt(sub2, 16, 0)
	v := (v1 + v2) / 2
	sub := fmt.Sprintf("%02X", v)
	copy(buf[1+2*i:3+2*i], sub)
}
c := string(buf[:])
155
Delete from filesystem the file having path filepath.
File.delete(filepath)
err := os.Remove(filepath)
156
Assign to the string s the value of the integer i in 3 decimal digits. Pad with zeros if i < 100. Keep all digits if i1000.
s = "%03d" % i
s := fmt.Sprintf("%03d", i)
157
Initialize a constant planet with string value "Earth".
Planet = 'Earth'
const planet = "Earth"
158
Create a new list y from randomly picking exactly k elements from list x.

It is assumed that x has at least k elements.
Each element must have same probability to be picked.
Each element from x must be picked at most once.
Explain if the original ordering is preserved or not.
y = x.sample(k)
y := make([]T, k)
perm := rand.Perm(len(x))
for i, v := range perm[:k] {
	y[i] = x[v]
}
159
Define a Trie data structure, where entries have an associated value.
(Not all nodes are entries)
type Trie struct {
	c        rune
	children map[rune]*Trie
	isEntry  bool
	value    V
}
160
Execute f32() if platform is 32-bit, or f64() if platform is 64-bit.
This can be either a compile-time condition (depending on target) or a runtime detection.
case 1.size
  when 8 then f64
  when 4 then f32
end
if strconv.IntSize==32 {
	f32()
}
if strconv.IntSize==64 {
	f64()
}
161
Multiply all the elements of the list elements by a constant c
elements.map { |el| el * c }
for i := range elements {
	elements[i] *= c
}
162
execute bat if b is a program option and fox if f is a program option.
bat if ARGV.include?("b")
fox if ARGV.include?("f")
var b = flag.Bool("b", false, "Do bat")
var f = flag.Bool("f", false, "Do fox")

func main() {
	flag.Parse()
	if *b {
		bar()
	}
	if *f {
		fox()
	}
}
163
Print all the list elements, two by two, assuming list length is even.
list.each_slice(2){|slice| p slice}
for i := 0; i+1 < len(list); i += 2 {
	fmt.Println(list[i], list[i+1])
}
164
Open the URL s in the default browser.
Set boolean b to indicate whether the operation was successful.
cmd = case  RbConfig::CONFIG['host_os']
  when  /mswin|mingw|cygwin/ then "start "
  when  /darwin/ then "open "
  when  /linux|bsd/ then "xdg-open "
  else raise "No OS detected"
end
    
b = system cmd + s
b := open.Start(s) == nil
Alternative implementation:
func openbrowser(url string) {
	var err error

	switch runtime.GOOS {
	case "linux":
		err = exec.Command("xdg-open", url).Start()
	case "windows":
		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", url).Start()
	case "darwin":
		err = exec.Command("open", url).Start()
	default:
		err = fmt.Errorf("unsupported platform")
	}
	if err != nil {
		log.Fatal(err)
	}

}
165
Assign to variable x the last element of list items.
x = items.last
Alternative implementation:
x = items[-1]
x := items[len(items)-1]
166
Create the list ab containing all the elements of the list a, followed by all the elements of the list b.
ab = a + b
ab := append(a, b...)
Alternative implementation:
var ab []T
ab = append(append(ab, a...), b...)
Alternative implementation:
ab := make([]T, len(a)+len(b))
copy(ab, a)
copy(ab[len(a):], b)
167
Create string t consisting of string s with its prefix p removed (if s starts with p).
t = s.sub(/\A#{p}/, "")
Alternative implementation:
t = s.delete_prefix(p)
t := strings.TrimPrefix(s, p)
168
Create string t consisting of string s with its suffix w removed (if s ends with w).
t = s.sub(/#{w}\z/, "")
Alternative implementation:
t = s.delete_suffix(w)
t := strings.TrimSuffix(s, w)
169
Assign to the integer n the number of characters of the string s.
Make sure that multibyte characters are properly handled.
n can be different from the number of bytes of s.
n = s.length
Alternative implementation:
n = s.size
n := utf8.RuneCountInString(s)
170
Set n to the number of elements stored in mymap.

This is not always equal to the map capacity.
n = mymap.size
n := len(mymap)
171
Append element x to the list s.
s << x
s = append(s, x)
172
Insert value v for key k in map m.
m[k] = v
m[k] = v
173
Number will be formatted with a comma separator between every group of thousands.
'1000'.gsub(/\B(?=(...)*\b)/, ',')
Alternative implementation:
1000.to_s(:delimited)
Alternative implementation:
'1000'.reverse.scan(/.{1,3}/).join(',').reverse
p := message.NewPrinter(language.English)
s := p.Sprintf("%d\n", 1000)
Alternative implementation:
n := strconv.Itoa(23489)
s := thousands.Separate(n, "en")
174
Make a HTTP request with method POST to the URL u
Net::HTTP.post(u, content)
response, err := http.Post(u, contentType, body)
Alternative implementation:
response, err := http.PostForm(u, formValues)
175
From array a of n bytes, build the equivalent hex string s of 2n digits.
Each byte (256 possible values) is encoded as two hexadecimal characters (16 possible values per digit).
s = a.unpack("H*")
Alternative implementation:
s = a.pack("c*").unpack("H*").first
s := hex.EncodeToString(a)
Alternative implementation:
s := fmt.Sprintf("%x", a)
176
From hex string s of 2n digits, build the equivalent array a of n bytes.
Each pair of hexadecimal characters (16 possible values per digit) is decoded into one byte (256 possible values).
[s].pack("H*").unpack("C*")
a, err := hex.DecodeString(s)
if err != nil {
	log.Fatal(err)
}
177
Construct a list L that contains all filenames that have the extension ".jpg" , ".jpeg" or ".png" in directory D and all it's subdirectories.
L = Dir.glob(File.join("**", "*.{jpg,jpeg,png}"), base: D)
L := []string{}
err := filepath.Walk(D, func(path string, info os.FileInfo, err error) error {
	if err != nil {
		fmt.Printf("failure accessing a path %q: %v\n", path, err)
		return err
	}
	for _, ext := range []string{".jpg", ".jpeg", ".png"} {
		if strings.HasSuffix(path, ext) {
			L = append(L, path)
			break
		}
	}
	return nil
})
178
Set boolean b to true if if the point with coordinates (x,y) is inside the rectangle with coordinates (x1,y1,x2,y2) , or to false otherwise.
Describe if the edges are considered to be inside the rectangle.
Point = Struct.new(:x, :y)

Rect  = Struct.new(:x1, :y1, :x2, :y2) do
  def contains?(point)
    point.x.between?(x1,x2) && point.y.between?(y1,y2)
  end
end

b = Rect.new(0,0,2,5).contains?(Point.new(0,0))
p := image.Pt(x, y)
r := image.Rect(x1, y1, x2, y2)
b := p.In(r)
179
Return the center c of the rectangle with coördinates(x1,y1,x2,y2)
Point = Struct.new(:x, :y)

Rect  = Struct.new(:x1, :y1, :x2, :y2) do
  def center  
    Point.new((x1+x2)/2.0, (y1+y2)/2.0)
  end
end

c = Rect.new(0,0,2,5).center
c := image.Pt((x1+x2)/2, (y1+y2)/2)
180
Create list x containing the contents of directory d.

x may contain files and subfolders.
No recursive subfolder listing.
x = Dir.children(d)
x, err := os.ReadDir(d)
182
Output the source of the program.
eval s="print 'eval s=';p s"
package main

import "fmt"

func main() {
	fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60)
}

var s = `package main

import "fmt"

func main() {
	fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60)
}

var s = `
183
Make a HTTP request with method PUT to the URL u
http = Net::HTTP.new(u)
response = http.send_request('PUT', path, body)
req, err := http.NewRequest("PUT", u, body)
if err != nil {
	return err
}
req.Header.Set("Content-Type", contentType)
req.ContentLength = contentLength
response, err := http.DefaultClient.Do(req)
184
Assign to variable t a string representing the day, month and year of the day after the current date.
t = (Date.today + 1).to_s
Alternative implementation:
t = 1.day.since.to_s
Alternative implementation: