How to add elements to php array

Method: 1. Use the array_unshift() function to insert one or more elements at the beginning of the array; 2. Use the array_push() function to insert one or more elements at the end of the array; 3. Use the array_merge() function to insert All elements of one array are inserted at the end of the other array.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Method 1: Use array_unshift() The function inserts elements at the beginning of the array

rray_unshift() function is used to insert one or more elements at the beginning of the array. Its syntax is as follows:

array_unshift ( array , value1 [, value2, value3 ... ] )

Parameter description:

• array represents an array;

• value1, value2, value3... represents the elements (values) that need to be inserted.

Return value: Returns the length of the array after inserting the new element.

Two points to note:

• The elements are inserted as a whole, and these elements will maintain the same order after insertion.

• All numeric key names will be modified to start counting from 0, and all string key names will remain unchanged.

Example:

<?php
$a=array("a"=>"red","b"=>"green");
array_unshift($a,"blue");
print_r($a);
?>

Output:

Array ( [0] => blue [a] => red [b] => green )

Method 2: Use the array_push() function to insert elements at the end of the array

array_push() function is used to insert one or more elements (push) at the end of the array. Its syntax is as follows:

array_push ( array , value1 [, value2, value3 ... ] )

Parameter description:

• array represents an array;

• value1, value2, value3... represents the elements (values) that need to be inserted.

Return value: Returns the length of the array after inserting the new element.

array_push() treats array as a stack and pushes the passed elements into the end of arr. The length of arr will be increased by the number of elements pushed onto the stack.

Example:

<?php
$a=array("red","green");
array_push($a,"blue","yellow");
print_r($a);
?>

Output:

Array ( [0] => red [1] => green [2] => blue [3] => yellow )

Method 3: Use array_merge() function

array_merge() function can The units of one or more arrays are combined, that is, the values ​​in one array are appended to the previous array, and the combined array is returned. The syntax format is as follows:

array_merge(array1 [, array2 [, array3 ...]])

• The parameters array1, array2,..., arrayyn are several arrays to be merged.

If the input array has the same string key name, the value after the key name will overwrite the previous value; if the array contains a numeric key name, the subsequent value will not The previous value is overwritten and appended instead; if the function has only one array parameter and the array is numerically indexed, the key names are re-indexed consecutively.

Example:

<?php
$a1=array("a"=>"red","b"=>"green");
$a2=array("c"=>"blue","b"=>"yellow");
print_r(array_merge($a1,$a2));
?>

Output:

Array
(
    [a] => red
    [b] => yellow
    [c] => blue
)

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