How to reverse php array-PHP Problem-php.cn

How to implement array reversal in php: 1. Use the "function reverse($arr){...}" method to achieve array reversal; 2. Use "function reverse_arr($arr){... }" method can be used to reverse the array.

How to reverse php array

#The operating environment of this article: Windows 7 system, PHP version 7.4, Dell G3 computer.

php implements array reversal

There is a function in php that can reverse an array, which is often used in work and is very convenient. Let’s implement this function by ourselves today.

$arr = [2,5,6,1,8,16,12]; function reverse($arr){ $left = 0; $right = count($arr) -1; $temp = []; while ($left <= $right){ $temp[$left] = $arr[$right]; $temp[$right] = $arr[$left]; $left++; $right--; } ksort($temp); return $temp; } 效果 Array ( [0] => 12 [1] => 16 [2] => 8 [4] => 6 [5] => 5 [6] => 2 )

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However, this function can only handle one-dimensional arrays. While implementing one that can handle multiple dimensions.

$arr = [2,[6,3,9],1,[5,2,1,[10,8,7]],5,0]; function reverse_arr($arr){ $index = 0; $reverse_array = []; foreach ($arr as $sub_arr){ if(is_array($sub_arr)){ $sub_arr = reverse($sub_arr); $arr_ = reverse_arr($sub_arr); $reverse_array[$index] = $arr_; }else{ $reverse_array[$index] = $sub_arr; } $index++; } return $reverse_array; } print_r(reverse(reverse_arr($arr))); 输出结果

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Array ( [0] => 0 [1] => 5 [2] => Array ( [0] => Array ( [0] => 7 [1] => 8 [2] => 10 ) [1] => 1 [2] => 2 [3] => 5 ) [3] => 1 [4] => Array ( [0] => 9 [1] => 3 [2] => 6 ) [5] => 2 )

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The above are all numeric index arrays and cannot handle associative arrays. Next comes the one that can handle associative arrays

$arr = ['a'=>'aa','b'=>'bb','c'=>'cc','d'=>'dd','e'=>'ee']; function reverse($arr){ $temp = []; end($arr); while (($value = current($arr)) != null){ $temp[key($arr)] = $value; prev($arr); } return $temp; } print_r(reverse($arr)); 结果 Array ( [e] => ee [d] => dd [c] => cc [b] => bb [a] => aa )

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