Arraylist sorting php array_map array function usage instructions

Copy code The code is as follows:

/*Function array_map() function: multiple array callback function---apply the callback function to the units of the given array
* 1. Syntax: array array_map (callback callback , array arr1 [, array ...] )
* 2. Description: Returns an array that contains the
* units of all units in arr1 after the callback has been applied. The number of arguments accepted by callback should match the number of arrays passed to the array_map() function.
* 3. Notes:
* 3.1. When a multi-array callback function acts on an array, the key name of the original array will be retained, that is, the key name of the returned array is
* the key name applied to the given array
* 3.2. When the multi-array return function operates on two or more arrays, their lengths must be consistent, and the
* key names of the original multiple arrays will be ignored, and the numeric index will be uniformly assigned as the key name
*/
// Example of using a single array
$websites=array("g"=>"google","b"=>"baidu","y"=>"yahoo");
//Output the original array
echo "

"; <br>print_r($websites); <br>echo "

";
//Define a callback function for processing a single array
function change_value($value){
return ucfirst($value) .".com";
}
$urls=array_map('change_value',$websites);
echo "

"; <br>print_r($urls); <br>echo "

";
/ /Examples of using multiple arrays
$arr1=array(1,3,5,7);
$arr2=array(2,4,6,8);
//Define callback functions for processing multiple arrays
function func1($a,$b){
return $a*$b;
}
$results=array_map('func1',$arr1,$arr2);
echo "After using the callback function to process multiple arrays, Returned results:
";
echo "

"; <br>print_r($results); <br>echo "

";

The operation effect is as follows:

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