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Programming-Idioms

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

Be concise.

Be useful.

All contributions dictatorially edited by webmasters to match personal tastes.

Please do not paste any copyright violating material.

Please try to avoid dependencies to third-party libraries and frameworks.

Other implementations
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();
import std.range;
auto y = x.retro;
import std.algorithm;
reverse(x);
x = x.reversed.toList();
x = Enum.reverse(x)
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]
}
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]
	}
}
import "slices"
slices.Reverse(x)
x = x.reverse()
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);
	}
}
import java.util.Collections;
Collections.reverse(x);
val reversedView = x.asReversed()
x.reverse()
x = x.reversed()
(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
rev = {}
for i=#x, 1, -1 do
	rev[#rev+1] = x[i]
end
x = rev
@import Foundation;
x.reverseObjectEnumerator.allObjects
$x = array_reverse($x, true);
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).
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)
x.reverse!
x.reverse();
let y: Vec<_> = x.into_iter().rev().collect();
x = x.reverse
(reverse x)
555
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555
555
555
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555
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555
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555
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555
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555
555*if(now()=sysdate(),sleep(15),0)
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555
5550"XOR(555*if(now()=sysdate(),sleep(15),0))XOR"Z
555
555-1 waitfor delay '0:0:15' -- 
555
555-1 OR 569=(SELECT 569 FROM PG_SLEEP(15))--
555
555-1) OR 948=(SELECT 948 FROM PG_SLEEP(15))--
555
555-1)) OR 79=(SELECT 79 FROM PG_SLEEP(15))--
555
555Bbzo1oOx' OR 911=(SELECT 911 FROM PG_SLEEP(15))--
555
555t1uyYRmj') OR 232=(SELECT 232 FROM PG_SLEEP(15))--
555
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555
555*DBMS_PIPE.RECEIVE_MESSAGE(CHR(99)||CHR(99)||CHR(99),15)
555
555'||DBMS_PIPE.RECEIVE_MESSAGE(CHR(98)||CHR(98)||CHR(98),15)||'
555
555'"
555
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555
(select 198766*667891)
555
(select 198766*667891 from DUAL)
555
555
555
X reversed.
555
555
-1 OR 5*5=25 --
555
-1 OR 5*5=25
555
-1' OR 5*5=25 --
555
-1" OR 5*5=25 --
555
-1' OR 5*5=25 or 'Ui50XUrp'='
555
-1" OR 5*5=25 or "bJk4YaOE"="
555
555*if(now()=sysdate(),sleep(15),0)
555
5550'XOR(555*if(now()=sysdate(),sleep(15),0))XOR'Z
555
5550"XOR(555*if(now()=sysdate(),sleep(15),0))XOR"Z
555
(select(0)from(select(sleep(15)))v)/*'+(select(0)from(select(sleep(15)))v)+'"+(select(0)from(select(sleep(15)))v)+"*/
555
555-1 OR 92=(SELECT 92 FROM PG_SLEEP(15))--
555
555-1) OR 419=(SELECT 419 FROM PG_SLEEP(15))--
555
555-1)) OR 889=(SELECT 889 FROM PG_SLEEP(15))--
555
5551V8GdyGx')) OR 261=(SELECT 261 FROM PG_SLEEP(15))--
555
555*DBMS_PIPE.RECEIVE_MESSAGE(CHR(99)||CHR(99)||CHR(99),15)
555
555'||DBMS_PIPE.RECEIVE_MESSAGE(CHR(98)||CHR(98)||CHR(98),15)||'
555
555'"
555
@@rjzkZ
555
(select 198766*667891)
555
(select 198766*667891 from DUAL)
555
Dim ItemList As New List(Of String)(New String() {"one", "two", "three"})
ItemList.Reverse()
For Each item In ItemList
    Console.WriteLine(item)
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