PHP commonly used array functions (3)

* 1. Split and merge

* 1. Split:array_chunk($arr,$num,[true]):$numThe number of elements in each group, true keeps the original index

* 2. Merge: array_merge($arr1,$arr2,...); associated key names with the same name will be automatically overwritten, and the index will be rearranged and automatically accumulated

* 2. Take out some elements

* 1.array_slice($arr, $offset, $length, true): Take out the specified number of elements from the specified position, true does not reset the index

* 3. Delete or replace some elements

* array_splice(&input,$offset [,$length=count($input) [,$replacement = array()]])

* Delete elements from the specified position, or replace them with new array elements

//1. Split: array_chunk($arr,$num,[true]): $num number of elements in each group, true keeps the original index

$arr = [3,5,10,4,'a'=>'中国','php',39,'mysql','java',true,[100,200,300]];

//Each group of 3 Split and keep the original index

// print_r(array_chunk($arr,3,true));

// 2. Merge: array_merge($arr1,$arr2,... );

$arr1 = ['name'=>'peter','course'=>'php','grade'=>60, 5=>'jQuery'];
$arr2 = ['name'=>'朱老师','sex'=>'男','grade'=>90,'job'=>'lecturer', 5=>'php'];

//The associated key names with the same name will be automatically overwritten, and the index key names will be rearranged and automatically accumulated, which is very suitable for user-defined configuration files to update system configuration

$arr1=array_merge($arr1, $arr2);//合并后再更新第一个数组
print_r($arr1); //查看合并后的数组,常用于配置文件更新操作

//3.array_slice ($arr, $offset, $length, true): Remove the specified number of elements from the specified position, true does not reset the numeric index

$arr2 = ['name'=>'朱老师','sex'=>'男','grade'=>90,'job'=>'lecturer', 5=>'php'];
print_r(array_slice($arr2,2,4)); //返回取出的元素组成的数组
print_r(array_slice($arr2,2,4,true)); //true: 不重置数字索引

//4.array_splice(&input,$offset): Delete or replace Partial elements

$city = ['北京', '上海', '广州', '深圳', '重庆', '天津'];

//Only keep the first 2 elements, and delete them starting from the index position 2: Guangzhou

print_r(array_splice($city, 2)); //返回删除
print_r($city);  //查看原数据,发现只有前二个元素啦
$city = ['北京', '上海', '广州', '深圳', '重庆', '天津'];

//The length is a negative number, which means from the negative number to the starting point elements, in this example -1 is Tianjin, 2,-1 refers to the data between Guangzhou and Chongqing

print_r(array_splice($city, 2,-1)); 
print_r($city);  //查看原数据,只前二个北京上海和最后一个天津
$city = ['北京', '上海', '广州', '深圳', '重庆', '天津'];
print_r(array_splice($city, -2, 1, ['合肥', '南京'])); //返回删除的重庆
print_r($city);  //查看原数据,重庆的位置由合肥,南京代替