PHP leaves array reference problem after foreach loop

The content of this article is about the reference problem of the array left by PHP after the foreach loop. Now I share it with you. Friends in need can take a look.

eg:

result:

Explanation:

1.foreach It is not a block-level field, the array reference ends, $k, $a does not release memory

2. When the first reference cycle ends, $a points to the last element of the array4

3 .When the loop starts for the second time (at this time $a already points to the last element and is a reference)

Loop 4 times. The changes in the array are:

1-> [1,2,3,4]

2-> [1,2,3,4]

3-> [1, 2,3,3] The third time value points to the last element 3 But value is a global reference pointing to the last element in the last cycle, so when value=3 it will also be The value of the last element is changed to 3

4-> [1,2,3,3]

# #Notes:

1. The implementation principle of foreach has the concept of internal pointers

2. When the foreach loop ends, the pointer will point to the last element

How to avoid:

After using &foreach loop unset ($a)

Related recommendations:

foreach reference passing address in PHP

Exception handling after using & reference in foreach in php

Analysis between foreach and normal for loop efficiency

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