How to add key-value pairs to php array

How to add key-value pairs to a php array: 1. Use the "array_pad ($arr, $size, $value)" statement; 2. Use the "array_unshift ($arr, $value)" statement; 3. Use the "array_push($arr,$value)" statement.

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

php array add key Value pair

1. Use array_pad() function

array_pad() function can fill the array to the specified length with a certain value. The syntax is as follows:

array_pad ( $arr, $size , $value )

Parameter description:

• arr represents the array to be filled.
• size represents the length to be filled:
  • If size is a positive number, fill to the right side of the array;
  • If size is a negative number, start from the left Filling;
  • If the absolute value of size is less than or equal to the length of the arr array, there will be no filling.
• value represents the value to be filled.

Example:

<?php
$arr = array(12, 10, 9);
var_dump($arr);
$result = array_pad($arr, 5, 0);  //从数组右侧开始, 用0填补数组到含有5个元素
var_dump($result);
$result = array_pad($arr, -7, -1);  //从数组左侧开始, 用-1填补数组到含有7个元素
var_dump($result);
$result = array_pad($arr, 2, "noop");  // 第二个参数小于数组长度, 不填补
var_dump($result);
?>

#2. Use array_unshift() function

array_unshift() function Used to insert one or more elements at the beginning of the array, the syntax is as follows:

array_unshift ( array &$arr , mixed $value1 [, mixed $value2, mixed $value3 ... ] )

Two points to note:

• The elements are inserted as a whole , these elements will remain in 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
header("Content-type:text/html;charset=utf-8");
$num = array(10, 45, 9);
var_dump($num);
array_unshift($num, 100, 6);  //在数组开头插入元素
var_dump($num);
?>

##3. Use the array_push() function

array_push ( array &$arr , mixed $value1 [, mixed $value2, mixed $value3 ... ] )

<?php
header("Content-type:text/html;charset=utf-8");
$num = array(10, 45, 9);
var_dump($num);
array_push($num, 100, 6);  //在数组开头插入元素
var_dump($num);
?>

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