PHP 常用数组函数

1.array_combine()生成一个数组,用一个数组的值作为键名,另一个数组值作为值；如：

$a1=array("a","b","c","d");
$a2=array("Cat","Dog","Horse","Cow");
print_r(array_combine($a1,$a2));

打印：Array ( [a] => Cat [b] => Dog [c] => Horse [d] => Cow )

2.合成后的数组 compact()创建一个由参数所带变量组成的；如：

  $firstname = "lopo";
       $lastname = "peter";
       $age = "18";
       $result = compact("firstname", "lastname", "age");
       print_r($result);

打印：Array ( [firstname] => lopo [lastname] => peter [age] => 18 )

3.数组合并和拆分

array_chunk() 把一个数组分割为新的数组块

$a=array("a"=>"Cat","b"=>"Dog","c"=>"Horse","d"=>"Cow");
print_r(array_chunk($a,2));//分割后的多维数组，规定每个新数组包含2个元素

打印：Array ( [0] => Array ( [0] => Cat [1] => Dog ) [1] => Array ( [0] => Horse [1] => Cow ) )

array_merge() 把两个或多个数组合并成一个数组

$a1=array("a"=>"Horse","b"=>"Dog");
$a2=array("c"=>"Cow","b"=>"Cat");
print_r(array_merge($a1,$a2));

打印：Array ( [a] => Horse [b] => Cat [c] => Cow )

4.array_slice() 在数组中根据条件取出一段值，并返回

$a=array(0=>"Dog",1=>"Cat",2=>"Horse",3=>"Bird");
print_r(array_slice($a,1,2)); //1为从'Cat'开始，2为返回两个元素

打印：Array ( [0] => Cat [1] => Horse )

5.array_diff() 返回两个数组的差集数组

  $a1=array(0=>"Cat",1=>"Dog",2=>"Horse");
       $a2=array(3=>"Horse",4=>"Dog",5=>"Fish");
       print_r(array_diff($a1,$a2));//返回$a1与$a2的不同之处

打印：Array ( [0] => Cat )

6.array_intersect() 返回两个或多个数组的交集数组

$a1=array(0=>"Cat",1=>"Dog",2=>"Horse");
$a2=array(3=>"Horse",4=>"Dog",5=>"Fish");
print_r(array_intersect($a1,$a2));//返回$a1与$a2的相同之处

打印：Array ( [1] => Dog [2] => Horse )

7.array_search() 在数组中查找一个键值

$a=array("a"=>"Dog","b"=>"Cat","c"=>"Horse");
print_r(array_search("Dog",$a));//成功返回键名,失败返回false;等同于in_array()

打印：a

8.array_splice() 把数组中一部分删除用其他值替代

  $a1=array(0=>"Dog",1=>"Cat",2=>"Horse",3=>"Bird");
       $a2=array(0=>"Tiger",1=>"Lion");
       array_splice($a1,0,2,$a2);//一个或多个数组 $a1被移除的部分由$a2补全；将原数组替换,注意替换后数组中键名不保留
       print_r($a1);

打印：Array ( [0] => Tiger [1] => Lion [2] => Horse [3] => Bird )

9.array_sum() 返回数组中所有值的总和

$a=array(0=>"5",1=>"15",2=>"25");
print_r(array_sum($a));

打印：45

10.array_key_exists() 判断数组中是否存在相应的key

$a=array("a"=>"Dog","b"=>"Cat","c"=>"Horse");
print_r(array_key_exists("a",$a));//返回true或false

打印：1

11.array_push() 向数组最后压入一个或多个元素

$a=array("Dog","Cat");
array_push($a,"Horse","Bird");
print_r($a);

打印：Array ( [0] => Dog [1] => Cat [2] => Horse [3] => Bird )

12.array_keys() 返回数组所有的键,组成一个数组

$a=array("a"=>"Horse","b"=>"Cat","c"=>"Dog");
print_r(array_keys($a));

打印：Array ( [0] => a [1] => b [2] => c )

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