php How to add an array element to an array

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The way to add elements ：1、 Use “array_unshift( Array , Array elements )” sentence , Add an element at the beginning of the array ;2、 Use “array_push( Array , Array elements )” sentence , Add elements at the end of the array ;3、 use “array_pad( Array , The length of the array +1, Elements )” sentence .

The operating environment of this tutorial ：windows7 System 、PHP7.1 edition 、DELL G3 The computer

php A method of adding an array element to an array

1、array_unshift() Function to insert a new element into the array

array_unshift($array,$value1,$value2...) The function can insert one or more new elements at the beginning of the array （ Key value ）.

Let's take a concrete look through the following examples ：

<?php$arr=array(10,12,20);array_unshift($arr,8);var_dump($arr);?>

array_unshift() The function does not maintain the original numerical index relationship , All key names will be deleted , And reassign it , From 0 Start counting again ; But all string key names remain the same .

<?phpheader("Content-type:text/html;charset=utf-8");$arr=array("a"=>"red","b"=>"green",3=>"pink");echo " The original array ：";var_dump($arr);array_unshift($arr,"blue");echo " Insert a new element at the beginning ：";var_dump($arr);?>

Output results ：

2、array_push() Function to insert a new element into the array

array_push($array,$value1,$value2...) The function can insert one or more elements at the end of the array （ Key value ）.

Let's take a concrete look through the following examples ：

<?php$arr=array(10,12,20);array_push($arr,8);var_dump($arr);?>

array_push() Functions and array_unshift() Different functions , It does not reset the numeric key name , Instead, count on the basis of the original numeric key name .

<?phpheader("Content-type:text/html;charset=utf-8");$arr=array("a"=>"red","b"=>"green",3=>"pink");array_push($arr,8,"9",3.14);var_dump($arr);?>

Output results ：

3、array_pad() Function to insert a new element into the array

array_pad($array,$size,$value) Function can take a key value $value Insert into array $array in , To fill the array to the specified length $size.（$size Parameters can be understood as the final number of elements in the array , That is, the length of the array after the insert operation ）.

Only need to $size Parameter set to Original array length +1 You can insert a new element

<?php$arr=array(10,12,20);$result =array_pad($arr,4,1);var_dump($result);?>

As can be seen from the above example ,array_pad() The function can insert elements at the end of the array , Actually array_pad() The function can also insert elements at the beginning of the array ; And the key is $size Parameters .

$size There are three values for parameters ：

• Is a positive number , Insert an element at the end of the array ;

• It's a negative number , Insert an element at the beginning of the array ;

• If its absolute value is less than or equal to $array Length of array , The insert operation is not performed .

<?php$arr=array(10,12,20);$result =array_pad($arr,-5,1);var_dump($result);$result =array_pad($arr,3,1);var_dump($result);$result =array_pad($arr,2,1);var_dump($result);?>

The output is ：

Parameters $value The value of can also be an array , Insert an entire array , Then the original array will become a two-dimensional array .

<?phpheader("Content-type:text/html;charset=utf-8");$arr=array(10,12,20);$result =array_pad($arr,-5,array(" Zhang San ",25," male "));var_dump($result);?>

The output is ：

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