[PHP-NOTES] note 130666 added to control-structures.foreach

The following C code mimics the reference leak behavior of a by-reference foreach loop in PHP. By intentionally leaving current pointing to the last element after the first loop, we can reproduce the same silent array corruption that occurs in PHP.

#include <stdio.h>
int main()
{
    int arr[] = {1, 2, 3, 4};
    int *current;

    //First Loop doubles the array
    for (size_t i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
    {
        //arr[i] === *(arr + i)
        arr[i] *= 2;
        current = arr + i;
        printf("Current modified:%d\n", *current);
    }

    /*
        After the loop completes, the arr is now {2,4,6,8}. 
        As for current, it is going to have the memory location of the last element (memory location of 8).
    */

    for (size_t i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
    {
        /*
            In each iteration, the memory location of 8 is going to be dereferenced and set to arr[i].
            As a result, the last value will be equal to the value before it
        */
        *current = arr[i];
        printf("Current:%d\n", *current);
    }

    return 0;
}

Just as PHP's $value remains a reference to the last element after a by-reference foreach, current here remains a pointer to arr[3]. Every iteration of the second loop writes into arr[3], ultimately copying the second-to-last value onto the last element.
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Server IP: 206.189.2.9
Probable Submitter: 83.171.206.236
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Manual Page -- https://php.net/manual/en/control-structures.foreach.php
Edit        -- https://main.php.net/note/edit/130666
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