PHP基础函数整理(数组一)

函数返回多个数组的差集数组,键名不进行比较,返回与第一个数组相比,第一个数组没有的值(数组)

形式:array_diff(array1,array2,array3...);

例子:

$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("e"=>"red","f"=>"black","g"=>"purple");
$a3=array("a"=>"red","b"=>"black","h"=>"yellow");
// $result=array_diff($a1,$a2,$a3);//Array ( [b] => green [c] => blue )
$result=array_diff($a1,$a2);//Array ( [b] => green [c] => blue [d] => yellow )

将数组的所有的键都转换为大写字母或小写字母

形式:array_change_key_case(array,case);

case可选值CASE_LOWER小写(默认) CASE_UPPER 大写

例子:

$age=array("Bill"=>"60","Steve"=>"56","Mark"=>"31");
print_r(array_change_key_case($age));// Array ( [bill] => 60 [steve] => 56 [mark] => 31 )
print_r(array_change_key_case($age,CASE_LOWER));// Array ( [bill] => 60 [steve] => 56 [mark] => 31 )
print_r(array_change_key_case($age,CASE_UPPER));//Array ( [BILL] => 60 [STEVE] => 56 [MARK] => 31 )

将数组按数量分为多个数组

形式:array_chunk(array,size[,preserve_key]);

preserve_key的参数:true保留原始键名 false(默认)不保留原始键名

例子:

$cars=array("Volvo","BMW","Toyota","Honda","Mercedes");
print_r(array_chunk($cars,2));
// Array ( [0] => Array ( [0] => Volvo [1] => BMW ) 
// [1] => Array ( [0] => Toyota [1] => Honda ) 
// [2] => Array ( [0] => Mercedes ) )

返回输入数组中某个单一列的值。

形式:array_column(array,column_key[,index_key]);

column_key:单列的键名

index_key:返回数组的索引,比如用id作为键名...不写则从零依次递加

例子:

$a = array(
array(
'id' => 5698,
'first_name' => 'Bill',
'last_name' => 'Gates',
),
array(
'id' => 4767,
'first_name' => 'Steve',
'last_name' => 'Jobs',
),
array(
'id' => 3809,
'first_name' => 'Mark',
'last_name' => 'Zuckerberg',
)
);
$last_names = array_column($a, 'last_name', 'id');
print_r($last_names);
//Array ( [5698] => Gates [4767] => Jobs [3809] => Zuckerberg )
//Array ( [0] => Gates [1] => Jobs [2] => Zuckerberg )

通过两个数组创建新的数组

形式:array_combine(keys,values);

第一个是键名,第二个是键值

键名与键值要数量相同,否则报错

例子:

$fname=array("Bill","Steve","Mark","ceshi");
$age=array("60","56","31","1");
$c=array_combine($fname,$age);
print_r($c);
// Array ( [Bill] => 60 [Steve] => 56 [Mark] => 31 [ceshi] => 1 )

用于统计数组中所有值出现的次数

形式:array_count_values(array)

例子:

$a=array("A","Cat","Dog","A","Dog");
print_r(array_count_values($a));
// Array ( [A] => 2 [Cat] => 1 [Dog] => 2 )