array_push（）和array_merge（）有什么区别？ [关闭]

Question

I am adding these two elements into a new array using these two functions array_push() and array_merge().

    $a1 = array();
    $a2 = 'foo';
    echo '<pre>';
    print_r( array_merge($a1, (array)$a2) );
    echo '</pre>';

And with ..

    $a1 = array();
    $a2 = 'foo';
    array_push($a1, $a2);
    echo '<pre>';
    print_r($a1);
    echo '</pre>';

all these are printing same..

Array
 (
    [0] => foo
 )

Now my question is what is the main difference between these two functions in functionality based. I am new in php, so please help me.

Answer 1

You can refer php manual, but for now i will explain you the difference like this.

array_push() treats array as a stack, and pushes the passed variables onto the end of array . The length of array increases by the number of variables pushed. Has the same effect as:

Example

<?php
$stack = array( "orange" , "banana" );
array_push
($stack , "1" , "2");
print_r ($stack );
?>
The above example will output:
Array
(
    [0] => orange
    [1] => banana
    [2] => 1
    [3] => 2
)

Array_merge() Merges the elements of one or more arrays together so that the values of one are appended to the end of the previous one. It returns the resulting array. If the input arrays have the same string keys, then the later value for that key will overwrite the previous one. If, however, the arrays contain numeric keys, the later value will not overwrite the original value, but will be appended. Values in the input array with numeric keys will be renumbered with incrementing keys starting from zero in the result array. Example

<?php
$array1 = array
("color" => "yellow" , 0, 1);
$array2 = array
("a" , "b" , "color" => "blue" , "shape
" =>"rectangle" , 1);
$result = array_merge
($array1 , $array2 );
print_r ($result );
?>

The above example will output:

Array
(
    [color] => blue
    [0] => 0
    [1] => 1
    [2] => a
    [3] => b
    [shape] => rectangle
    [4] => 1
)

array_push — Push one or more elements onto the end of array

array_push() treats array as a stack, and pushes the passed variables onto the end of array. The length of array increases by the number of variables pushed.

array_merge — Merge one or more arrays

Merges the elements of one or more arrays together so that the values of one are appended to the end of the previous one. It returns the resulting array.

    <?php
    $a1 = array('foo', 'bar');
    $a2 = 'foo';
    echo '<br />';
    print_r( array_merge($a1, (array)$a2) );
    $a1 = array('foo', 'bar');
    $a2 = 'foo';
    echo '<br />';
    array_push($a1, $a2);
    print_r($a1);
    ?>

As per performance array_merge is slow.There is a discussion you should read.