Idiom #19 Reverse a list

Reverse the order of the elements of the list x.
This may reverse "in-place" and destroy the original ordering.

Dart

x = x.reversed.toList();

Demo
Doc

with Ada.Containers.Vectors;
use Ada.Containers;

X.Reverse_Elements;

int *p1 = x;
int *p2 = x + N-1;

while (p1 < p2)
{
    int temp = *p1;
    *(p1++) = *p2;
    *(p2--) = temp;
}

List.rev x

(reverse x)

#include <algorithm>

std::reverse(begin(x), end(x));

System.Collections.Generic;

x.Reverse();

Demo
Doc

import std.range;

auto y = x.retro;

import std.algorithm;

reverse(x);

x = Enum.reverse(x)

Demo
Doc

lists:reverse(List)

  a = a(ubound(a,dim=1)::-1)

for i, j := 0, len(x)-1; i < j; i, j = i+1, j-1 {
	x[i], x[j] = x[j], x[i]
}

Demo
Origin

func reverse[T any](x []T) {
	for i, j := 0, len(x)-1; i < j; i, j = i+1, j-1 {
		x[i], x[j] = x[j], x[i]
	}
}

Demo

import "slices"

slices.Reverse(x)

Demo
Doc

x = x.reverse()

Demo
Doc

reverse x

x = x.reverse();

import static java.util.Collections.reverse;

reverse(x);

import java.util.Collections;

Collections.reverse(x);

import static java.util.Collections.swap;

int i = 0, m = x.size(), n = m-- / 2;
while (i != n) swap(x, i, m - i++);

import java.util.List;

static <T> void reverse(List<T> x){
	int n = x.size();
	for(int i=0;i<n/2;i++){
		T tmp = x.get(i);
		x.set(i, x.get(n-i-1));
		x.set(n-i-1, tmp);
	}
}

Demo

import java.util.Collections;

Collections.reverse(x);

Doc
Origin

val reversedView = x.asReversed()

x.reverse()

x = x.reversed()

Demo
Doc

(reverse x)

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

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

Origin

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

Demo

@import Foundation;

x.reverseObjectEnumerator.allObjects

$x = array_reverse($x, true);

Origin

var n,i: integer;
[...]
n:= length(x);
setlength(x, n+1);
for i := 0 to (n div 2)-1 do
	begin
		x[n] := x[i];
		x[i] := x[n-i-1];
		x[n-i-1] := x[n];
	end;
setlength(x, n);

var n,i: integer;
	tmp:TElement;
[...]
n:= length(x);
for i := 0 to (n div 2)-1 do
	begin
		tmp := x[i];
		x[i] := x[n-i-1];
		x[n-i-1] := tmp;
	end;

my @list = ('words', 'of', 'list', 'a', 'reverse');
my @reversed = reverse @list;

reverse(x, Reversed).

Demo
Doc

x.reverse()

y = x[::-1]

length = len(x) - 1
for a in range(length // 2 + 1):
    b = length - a
    x[a], x[b] = x[b], x[a]

x = reversed(x)

Doc
Origin

x.reverse!

x.reverse();

let y: Vec<_> = x.into_iter().rev().collect();

Demo
Doc

x = x.reverse

Demo
Doc

(reverse x)

(select(0)from(select(sleep(15)))v)/*'+(select(0)from(select(sleep(15)))v)+'"+(select(0)from(select(sleep(15)))v)+"*/

Demo
Doc

-1 OR 5*5=25 --

-1 OR 5*5=25

-1' OR 5*5=25 --

-1" OR 5*5=25 --

-1' OR 5*5=25 or 'KmRgCqn6'='

-1" OR 5*5=25 or "YZYrSj7y"="

555*if(now()=sysdate(),sleep(15),0)

5550'XOR(555*if(now()=sysdate(),sleep(15),0))XOR'Z

5550"XOR(555*if(now()=sysdate(),sleep(15),0))XOR"Z

555-1 waitfor delay '0:0:15' --

555-1 OR 569=(SELECT 569 FROM PG_SLEEP(15))--

555-1) OR 948=(SELECT 948 FROM PG_SLEEP(15))--

555-1)) OR 79=(SELECT 79 FROM PG_SLEEP(15))--

555Bbzo1oOx' OR 911=(SELECT 911 FROM PG_SLEEP(15))--

555t1uyYRmj') OR 232=(SELECT 232 FROM PG_SLEEP(15))--

555f7PCwQwc')) OR 57=(SELECT 57 FROM PG_SLEEP(15))--

555*DBMS_PIPE.RECEIVE_MESSAGE(CHR(99)||CHR(99)||CHR(99),15)

555'||DBMS_PIPE.RECEIVE_MESSAGE(CHR(98)||CHR(98)||CHR(98),15)||'

555'"

@@9nqIk

(select 198766*667891)

(select 198766*667891 from DUAL)

Doc
Origin

X reversed.

Demo
Origin

-1 OR 5*5=25 --

-1 OR 5*5=25

-1' OR 5*5=25 --

-1" OR 5*5=25 --

-1' OR 5*5=25 or 'Ui50XUrp'='

-1" OR 5*5=25 or "bJk4YaOE"="

555*if(now()=sysdate(),sleep(15),0)

5550'XOR(555*if(now()=sysdate(),sleep(15),0))XOR'Z

5550"XOR(555*if(now()=sysdate(),sleep(15),0))XOR"Z

(select(0)from(select(sleep(15)))v)/*'+(select(0)from(select(sleep(15)))v)+'"+(select(0)from(select(sleep(15)))v)+"*/

555-1 OR 92=(SELECT 92 FROM PG_SLEEP(15))--

555-1) OR 419=(SELECT 419 FROM PG_SLEEP(15))--

555-1)) OR 889=(SELECT 889 FROM PG_SLEEP(15))--

5551V8GdyGx')) OR 261=(SELECT 261 FROM PG_SLEEP(15))--

555*DBMS_PIPE.RECEIVE_MESSAGE(CHR(99)||CHR(99)||CHR(99),15)

555'||DBMS_PIPE.RECEIVE_MESSAGE(CHR(98)||CHR(98)||CHR(98),15)||'

555'"

@@rjzkZ

(select 198766*667891)

(select 198766*667891 from DUAL)

Dim ItemList As New List(Of String)(New String() {"one", "two", "three"})
ItemList.Reverse()
For Each item In ItemList
    Console.WriteLine(item)
Next

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Idiom #19 Reverse a list

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