PHP array copy and Reference Assignment, php array assignment

PHP array copy and Reference Assignment, php array assignment

 

1. When the PHP array variable $ arr is assigned to another variable $ one, the array variable $ arr is copied to $ one, even if $ arr is a multi-dimensional array.

Example:

$ Arr = array (1, 2, 3, array ('one', 'two'); $ one = $ arr;
# Output the original array $ arrprint_r ($ arr ); # Array ([0] => 1 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => two ))

# Output new array $ one
Print_r ($ one ); # Array ([0] => 1 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => two ))

# Modify the original array $ arr and output $ arr [0] = 4; $ arr [3] [1] = 'three '; print_r ($ arr ); # Array ([0] => 4 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => three ))

# Output a new array $ oneprint_r ($ one ); # Array ([0] => 1 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => two ))

The example shows that modifying the value of the original array does not affect the new array.

2. When the PHP array variable $ arr assigns a reference value to another variable $ one, $ arr does not copy the array variable $ one, instead, assign the array reference to $ one, that is, two variables point to the same array.
Example:

$ Arr = array (1, 2, 3, array ('one', 'two'); $ one = & $ arr; # output the original array $ arrprint_r ($ arr ); # Array ([0] => 1 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => two )) # output a new array $ oneprint_r ($ one ); # Array ([0] => 1 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => two )) # modify the original array $ arr and output $ arr [0] = 4; $ arr [3] [1] = 'three '; print_r ($ arr ); # Array ([0] => 4 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => three )) # output a new array $ oneprint_r ($ one ); # Array ([0] => 4 [1] => 2 [2] => 3 [3] => Array ([0] => one [1] => three ))

The example shows that the value of the original array is modified, and the value of the new array is also changed.

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