How to modify the values ​​of multiple elements in an array in php

Two modification methods: 1. Use array_splice() to replace the new value. The syntax is "array_splice(array, starting position, replacement number, replacement array)". The number of replacements and the number of elements in the replacement array must be consistent. 2. Use array_map() to call a user-defined function to modify one or more values.

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

php has many modification arrays Two methods for element values

Method 1: Use the array_splice() function to replace the array value

array_splice($array,$start,$length,$replacement)

Use the array_splice() function to replace the array value from Specify the position$startStart replacing the specified number of array elements (the length value and the number of replacements need to be consistent)

Therefore, if multiple values ​​are replaced, replace the value$ replacement can be set to an array.

Example:

<?php
$arr=array(1,2,3,4,5);
var_dump($arr);
array_splice($arr,1,3,array("A","B","D"));
var_dump($arr);
?>

Method 2: Use the array_map() function to call a user-defined function to modify one or more values

array_map(myfunction,array)

array_map() function applies the user-defined function to each value in the array, and returns the array with the new value after the user-defined function is applied.

Example 1: Modify all array elements

<?php
function f($num){
	return($num+2);
}

$arr=array(1,2,3,4,5);
var_dump($arr);
var_dump(array_map("f",$arr));
?>

Example 2: Double even numbers

<?php
function f($num){
	if($num%2==0){
		return($num*$num);
	}
	return $num;
}

$arr=array(1,2,3,4,5);
var_dump($arr);
var_dump(array_map("f",$arr));
?>

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