I want to know how to reverse an array without using the array_reverse method. I have an array called reverse array which is the one i want to reverse. My code is below. could someone point out what i am doing wrong as I cannot find any example of reversing an array this way anywhere else. my code is below.
<?php
//Task 21 reverse array
$reverseArray = array(1, 2, 3, 4);
$tmpArray = array();
$arraySize = sizeof($reverseArray);
for($i<arraySize; $i=0; $i--){
echo $reverseArray($i);
}
?>
<?php
$array = array(1, 2, 3, 4);
$size = sizeof($array);
for($i=$size-1; $i>=0; $i--){
echo $array[$i];
}
?>
Below is the code to reverse an array, The goal here is to provide with an optimal solution. Compared to the approved solution above, my solution only iterates for half a length times. though it is O(n) times. It can make a solution little faster when dealing with huge arrays.
<?php
$ar = [34, 54, 92, 453];
$len=count($ar);
for($i=0;$i<$len/2;$i++){
$temp = $ar[$i];
$ar[$i] = $ar[$len-$i-1];
$ar[$len-$i-1] = $temp;
}
print_r($ar)
?>
The problem with your method is when you reach 0, it runs once more and index gets the value of -1.
$reverseArray = array(1, 2, 3, 4); $arraySize = sizeof($reverseArray); for($i=$arraySize-1; $i>=0; $i--){ echo $reverseArray[$i]; }
Here's another way in which I borrow the code from here and update it so that I eliminate having to use a $temp variable and instead take advantage of array destructuring, as follows:
<?php
/* Function to reverse
$arr from start to end*/
function reverseArray(&$arr, $start,
$end)
{
while ($start < $end)
{
[$arr[$start],$arr[$end]] = [$arr[$end],$arr[$start]];
$start++;
$end--;
}
}
$a = [1,2,3,4];
reverseArray($a,0,count($a)-1);
print_r($a);
See live code
One of the advantages of this technique is that the array $a is reversed in place so there is no necessity of creating a new array.
The following improves the code so that one need not pass more than one parameter to reverseArray(); as well as indicating that there is no return value:
/* Function to reverse
$arr from start to end*/
function reverseArray(&$arr, $start=0): void
{
$end = count($arr)-1;
while ($start < $end)
{
[$arr[$start],$arr[$end]] = [$arr[$end],$arr[$start]];
$start++;
$end--;
}
}
$a = [1,2,3,4];
reverseArray($a);
print_r($a);
See here
Note: this revision works in PHP 7.2-7.4.2
Reverse an array in php WITHOUT using any function the array reverse method
<?php
$array = [11,22,32,42,52,62,71];
$count = sizeof($array);
for($i = $count -1;$i >=0;$i--){
$data[] = $array[$i];
}
print_r($data);
?>
how to reverse a array without using any predefined functions in php.. i had a solution for this problem... here is my solution........
<?php
// normal array --------
$myarray = [1,2,3,4,5,6,7,8,9];
//----------------
$arr = [];
for($i=9; $i > -1; $i--){
if(!$i==0){
$arr[]= $i;
}
}
print_r($arr);
//the out put is [9,8,7,6,5,4,3,2,1];
?>
