Programming-Idioms.org

print("Hello World")

for i=1, 10 do
	print('Hello')
end

print(("Hello\n"):rep(10))

print(string.rep("Hello\n", 10))

local i = 0
repeat
	i = i + 1
	print("Hello")
until i == 10

function finish(name)
	print('My job here is done. Goodbye, '..name..'.')
end

function square(x)
	return x*x
end

point = { x = 123, y = 456 }

for _, x in ipairs(items) do
	print(x)
end

for i, x in ipairs(items) do
	print('Index: '..i..', Value: '..x)
end

x = {one = 1, two = 2}

local function BinTree(v, l, r)
	return {
		val = v,
		left = l,
		right = r
	}
end

shuffled = {}
for i, v in ipairs(x) do
	local pos = math.random(1, #shuffled+1)
	table.insert(shuffled, pos, v)
end

function(x)
	for i = #x, 2, -1 do
		local j = math.random(i)
		x[i], x[j] = x[j], x[i]
	end
end

x[math.random(#x)]

function contains(list, x)
	for _, v in pairs(list) do
		if v == x then return true end
	end
	return false
end

for k, x in pairs(mymap) do
	print('Key: '..k..', Value: '..x)
end

function pick(a,b)
	return a + (math.random()*(b-a))
end

math.random(a, b)

local function dfs(bt, f, ...)
  local tt = type(bt)
  if tt~='table' and tt~='userdata' then return end
  dfs(t.left, f, ...)
  f(t.data, ...)
  dfs(t.right, f, ...)
end

local function Tree(v, c)
	return {
		val = v,
		children = c
	}
end

rev = {}
for i=#x, 1, -1 do
	rev[#rev+1] = x[i]
end
x = rev

rev = {}
for i=#x, 1, -1 do
	rev[#rev+1] = x[i]
end

-- in-situ reversal
function reverse(t)
  local n = #t
  local i = 1
  for i = 1, n do
    t[i],t[n] = t[n],t[i]

    n = n - 1
  end
end

function array_reverse(x)
  local n, m = #x, #x/2
  for i=1, m do
    x[i], x[n-i+1] = x[n-i+1], x[i]
  end
  return x
end

function search(m, x)
   for i,v1 in ipairs(m) do
      for j,v2 in ipairs(v1) do
         if v2 == x then return i,j end
      end
   end
end

a, b = b, a

i = tonumber(s)

s = string.format("%.2f",x)

s = 'ネコ'

local x = setmetatable({},{
   __index = function(t1,k1)
      t1[k1] = setmetatable({},{
         __index = function(t2,k2)
            t2[k2] = 0
            return t2[k2]
         end
      })
      return t1[k1]
   end
})

x = {}
for i=1,m do
  x[i] = {}
  for j=1,n do
    x[i][j] = 0
  end
end

local x = {}
for i=1,m do
   x[i] = {}
   for j=1,n do
      x[i][j] = {}
      for k=1,p do
         x[i][j][k] = 0
      end
   end
end

table.sort(items, function(a,b)
	if a.p < b.p then return true end
end)

local removedItem = table.remove(items,i)

function f(n)
   local function f_(factorial,n)
      if n < 2 then return 1
      return f_(factorial*n, n-1)
   end
   return f_(1,n)
end

function exp(x, n)
    return x^n
end

function compose(f,g)
   return function(x)
      return g(f(x))
   end
end

function compose(f,g)
   return function(x)
      return g(f(x))
   end
end

function curry2(f)
   return function(a)
      return function(b)
         return f(a,b)
      end
   end
end

function add(a,b)
   return a + b
end

local curryAdd = curry2(add)
local add2 = curryAdd(2)

local unpack = unpack or table.unpack
local function aux_ncurry(n, m, fn, args)
  if m>n then return fn(unpack(args,1,n))end
  local new_args, new_m = {}, m
  for i=1,m-1 do new_args[i]=args[i]end
  return function(a) 
    new_args[new_m]=a
    return aux_ncurry(n, new_m + 1, fn, new_args)
  end
end
local function ncurry(n, fn) return aux_ncurry(n,1,fn,{}) end

local t = s:sub(i, j - 1)

ok = s:find(word, 1, true)

ok = false
if s:find(word, 1, true) then ok = true end

ok = s:find(word, 1, true) ~= nil

function utf8.reverse(s)
	local r = ""
	for p,c in utf8.codes(s) do
		r = utf8.char(c)..r
	end
	return r
end

t = utf8.reverse(s)

breakout = false
for i,v1 in ipairs(m) do
   for j,v2 in ipairs(v1) do
      if v2 < 0 then
         print(v2)
         state = "found"
         breakout = true
         break
      end
   end
   if breakout then break end
end

table.insert(s,i,x)

local start = os.clock()
while os.clock() - start < 5 do end

os.execute(package.config:sub(1,1) == "/" and "sleep 5" or "timeout 5")

t = s:sub(1,5)

s = [[
Huey
Dewey
Louie
]]

s = 'Huey \n'..
'Dewey \n'..
'Louie'

chunks = {}
for substring in s:gmatch("%S+") do
   table.insert(chunks, substring)
end

while true do 
	-- Do something
end

m[k] ~= nil

y = table.concat(x, ", ")

s = 0
for i,v in ipairs(x) do
   s = s + v
end

s = tostring(i)

y = {}
for _, v in ipairs(x) do
	if p(v) then y[#y+1] = v end
end

lines = io.input(f):read('a')

io.stderr:write(string.format("%d is negative\n",x))

x = arg[1]

d = os.date()

i = x:find(y)

x2 = x:gsub(y,z)

s = string.format("%.1f%%", x*100)

math.randomseed(s)

math.randomseed( os.time() )

print( table.concat( arg, " " ) )

function gcd(x, y)
	if (y == 0) then
		return x
	else 
		return gcd(y, x%y)
	end
end

function gcd(a, b)
	return b==0 and a or gcd(b,a%b)
end

local s = {}

while x > 0 do
    local tmp = math.fmod(x,2)
    s[#s+1] = tmp
    x=(x-tmp)/2
end

s=table.concat(s)

repeat
	someThing()
	someOtherThing()
until not c

y = x + .0

y = (16 ^ 13) + x - (16 ^ 13)

y = math.modf(x)

function round(float)
    local int, part = math.modf(float)
    if float == math.abs(float) and part >= .5 then return int+1    -- positive float
    elseif part <= -.5 then return int-1                            -- negative float
    end
    return int
end

function round(float)
    return math.floor(float + .5)
end

r = "htt+p"

os.exit()

return nil, "Invalid argument x"

local Foo = {}
do
	local x = 0
	Foo.getX = function()
		return x
	end
end
print(Foo.getX()) -- 0
print(x) -- nil

local function Foo()
    local private = {x = 9}
    local mt = {
        __index = private,
        __newindex = function (t, k, v)
            error("attempt to update a read-only table", 2)
        end
    }
    return setmetatable({}, mt)
end

local foo = Foo()
print(foo.x) -- 9
foo.x = 3    -- error: attempt to update a read-only table

file = io.open("data.json")
x = cjson.decode(file:read("a"))
file:close()

file = io.open("data.json", "w")
file:write(cjson.encode(x))
file:close()

function control(f)
	f()
end

print(type(x))

b = s:find(prefix, 1, true) == 1

function startswith(text, prefix)
    return text:find(prefix, 1, true) == 1
end

b = startswith(s, prefix)

b = string.sub(s, 1, #prefix) == prefix

b = s:sub(-string.len(suffix)) == suffix

x = os.date("%F",d)

table.sort(items,c)

s = arg[0]

dir = os.getenv("PWD") or io.popen("cd"):read()

dir = arg[1]

if x then print(x) end

 blank = (s == nil or #string.gsub(s, "^%s*(.-)%s*$", "%1") == 0)

os.execute(x .. 'a b')

for k, x in pairs(mymap) do
  print(k, x)
end

s2 = s1:gsub(w,"")

local n = #x

local hash = {}
local y = {}
for _,v in ipairs(x) do
   if (not hash[v]) then
       y[#y+1] = v
       hash[v] = true
   end
end

local seen = {}
for index,item in ipairs(x) do
	if seen[item] then
		table.remove(x, index)
	else
		seen[item] = true
	end
end

n = io.read("n")

Suit = {
    SPADES=1,
    HEARTS=2,
    DIAMONDS=3,
    CLUBS=4
}

assert(isConsistent() , "Assertion violation") 

function foo()
	return "bar", false
end

if (c1) then f1()
elseif (c2) then f2()
elseif (c3) then f3()
end

ok = string.find( string.lower(s), string.lower(word) ) and true or false

items = {a, b, c}

b = tonumber(s) ~= nil

file = io.tmpfile()

m[k]=nil

s = string.format("%x",x)

function exists(name)
    if type(name)~="string" then return false end
    return os.rename(name,name) and true or false
end

if string.sub(p, -1, -1) == "/" then
	p=string.sub(p, 1, -2)
end

s = c

t = s .. i

local c = "#"
for i=2,#c1,2 do
	local avg = (tonumber(c1:sub(i,i+1), 16) + tonumber(c2:sub(i,i+1), 16)) / 2
	c = c .. string.format("%02x", math.floor(avg))
end

os.remove(filepath)

PLANET = "Earth"

local x = items[#items]

ab = {}

table.foreach(a, function(k, v) table.insert(ab, v) end)
table.foreach(b, function(k, v) table.insert(ab, v) end)

ab = {}

table.move(a, 1, #a, 1, ab)
table.move(b, 1, #b, #ab + 1, ab)

local t = (s:sub(0, #p) == p) and s:sub(#p+1) or s

local t = s:gsub(w.."$", "")

local n = utf8.len(s)

local n=0
for _ in pairs(mymap) do n=n+1 end

s[#s + 1] = x

table.insert(s, x)

x = [["x = [" .. "[" .. x .. "]" .. "]\nprint(" .. x)]]
print("x = [" .. "[" .. x .. "]" .. "]\nprint(" .. x)

os.exit(0)

local a = {}

for x = 1, n do
  local t = {}
  for y = 1, m do
    t[y] = {x, y}
  end
  a[x] = t
end
  
local b = {}

for y = 1, m do
  local t = {}
  for x = 1, n do
    t[x] = a[x][y]
  end
  b[y] = t
end

os.exit(x)

local h = math.sqrt(x^2 + y^2)

local function frexp(a)
	return math.frexp(a)
end

foo = os.getenv("FOO") or "none"

print(_VERSION)

local t = s:gsub("%s+", " ")

local t

table.insert(items, 1, x)

function f( x )
	if x then
		print("Present", x)
	else
		print("Not present")
	end
end

local c = {}
for i=1,#a do
	c[i] = string.char(string.byte(a, i) ~ string.byte(b, i))
end
c = table.concat(c)

print(table.concat(a,", "))

for i=5, 0, -1 do
	print(i)
end

n=1
while(n<=100) do
    out=""
    if(n%3==0) then
        out=out .. "Fizz"
    end
    if(n%5==0) then
        out=out .. "Buzz"
    end
    if(out=="") then
        out=out .. tostring(n)
    end
    print(out)
    n=n+1
end

x[e] = true

local a = 0/0

local s = a..b

local t = string.lower(s)

local t = string.upper(s)