Issues referenced in foreach

I encountered a problem about the PHP foreach reference at work.

Simply put, the following code

 

$arr=array(‘a‘,‘b‘,‘c‘ ,‘d‘);foreach($arr as $k=>&$v){　　........} foreach($arr as $k=>$v){........} print_r($arr);

 

 

The result is

A

B

C

C

 

Refer to this article and this article

After the first foreach traversal, the value of $ V is 'D' and the corresponding key is 3. Note that $ V is referenced here.

When the second foreach traverses the first element, $ v = 'A', then according to the reference, $ arr [3] = 'A'

The value of $ arr is

0

1 B

2 C

3

When traversing the second element, $ v = 'B', then according to the reference, $ arr [3] = 'B'

The value of $ arr is

0

1 B

2 C

3 B

When traversing the third element, $ v = 'C', then according to the reference, $ arr [3] = 'C'

The value of $ arr is

0

1 B

2 C

3 C

 

When traversing the third element, $ v = 'C', then according to the reference, $ arr [3] = 'C'

At this time, the value of $ arr is, and it remains unchanged

0

1 B

2 C

3 C

 

Solution:

After the first foreach, add unset ($ V );