PHP recursive function Introduction to Array related functions in PHP

1. Use the function array_keys() to get all the keys in the array, parameter: array

$arr=array();
$arr['one']="one";
$arr['two']="two";
$arr['three']="three";
$newArr=array_keys($arr);
print_r($newArr);
//Array ( [0] => one [1] => two [2] => three )

2. Use the function array_values() to get all the values ​​in the array, parameter: array

$arr=array();
$arr[20]="one";
$arr[30]="two";
$arr[40]="three";
$newArr=array_values($arr);
print_r($newArr);
//Array ( [0] => one [1] => two [2] => three )

3. Use the function array_map (), so that each element calls a custom function, parameters: String type function name, array

$arr=array();
$arr[0]="one";
$arr[1]="two";
$arr[2]="three";
function test($v){
  return $v." Hello";
}
$newArr=array_map("test",$arr);
print_r($newArr);
//Array ( [0] => one Hello [1] => two Hello [2] => three Hello )

4. Use the function array_merge() to merge two arrays into one, parameters: array, array
associative array When merging, those with the same key will be overwritten by the subsequent array. When the index arrays are merged, they will be connected together to form a new array.

$arr=array();
$arr[0]="one";
$arr[1]="two";
$arr[2]="three";
$arr1=array();
$arr[3]="taoshihan1";
$arr[4]="taoshihan2";
$arr[5]="taoshihan3";
$newArr=array_merge($arr,$arr1);
print_r($newArr);
//Array ( [0] => one [1] => two [2] => three [3] => taoshihan1 [4] => taoshihan2 [5] => taoshihan3 )
$arr=array("one","two","three");
$arr1=array("4","5","6");
$newArr=array_merge($arr,$arr1);
print_r($newArr);
//Array ( [0] => one [1] => two [2] => three [3] => 4 [4] => 5 [5] => 6 )

5. Use the function ksort() to sort according to the key name. Note that no new ones are returned. Arrays are still the original arrays

$arr=array("2"=>"taoshihan2","1"=>"taoshihan1","3"=>"taoshihan3");
ksort($arr);
print_r($arr);
//Array ( [1] => taoshihan1 [2] => taoshihan2 [3] => taoshihan3 )
使用函数array_search()，搜索某个键值，返回对应的键
$arr=array("2"=>"taoshihan2","1"=>"taoshihan1","3"=>"taoshihan3");
echo array_search("taoshihan1",$arr);
// 1

The above introduces the php recursive function Array related functions in PHP, including the content of php recursive functions. I hope it will be helpful to friends who are interested in PHP.

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