数组相关处理函数

向右看齐 2021-12-09 20:53 260阅读 0赞

一、数组键值相关处理函数

1. array\_values()　　//返回输入的所有值，并建立索引

1 $temp=array("os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "laguage"=>"php");
 2 $arr=array_values($temp);
 3 echo '<pre>';
 4 print_r($arr);
 5 echo '</pre>';
 6 
 7 //result
 8 Array
 9 (
 10 [0] => linux
 11 [1] => Apache
 12 [2] => MySql
 13 [3] => php
 14 )

2. array\_keys()　　//返回数组中所有的键名

array\_keys(inputarray,\[mixed value\])　　//若指定要搜索的值，则返回该值的键名，否则返回全部

1 $temp=array("os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "laguage"=>"php");
 2 $arr=array_keys($temp);
 3 echo '<pre>';
 4 print_r($arr);
 5 echo '</pre>';
 6 
 7 $arr=array_keys($temp, "MySql");
 8 echo '<pre>';
 9 print_r($arr);
 10 echo '</pre>';
 11 
 12 //value
 13 Array
 14 (
 15 [0] => os
 16 [1] => webserver
 17 [2] => db
 18 [3] => laguage
 19 )
 20 Array
 21 (
 22 [0] => db
 23 )

3. bool **in\_array** ( mixed needle, array haystack \[, bool strict\])

//检查数组中是否存在某个值

1 $temp=array("os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "laguage"=>"php");
 2 if( in_array("Apache", $temp) ){
 3 echo 'find Apache!'.' ';
 4 }
 5 
 6 //result
 7 find Apache!

4. bool **array\_key\_exists** ( mixed key, array search)

//检查给定的键名或者索引是否存在于数组中

$temp=array("os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "language"=>"php");
 if( array_key_exists("language", $temp) ){
 echo 'language is in array!'.' ';
 }
 
 //result
 
 language is in array!

5. array **array\_flip** ( array trans)

//交换数组中的键和值

1 $temp=array("os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "language"=>"php");
 2 
 3 echo ' ';
 4 print_r($temp);
 5 echo ' ';
 6 
 7 $temp=array_flip($temp);
 8 echo ' ';
 9 print_r($temp);
 10 echo ' ';
 11 
 12 //result
 13 Array ( [os] => linux [webserver] => Apache [db] => MySql [language] => php ) 
 14 
 15 Array ( [linux] => os [Apache] => webserver [MySql] => db [php] => language )

6. array **array\_reverse** ( array array \[, bool preserve\_keys\])

//返回一个单元顺序相反的数组

1 $temp=array("os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "language"=>"php");
 2 
 3 $temp=array_reverse($temp);
 4 echo '<pre>';
 5 print_r($temp);
 6 echo '</pre>';
 7 
 8 $temp=array_reverse($temp);
 9 echo '<pre>';
 10 print_r($temp);
 11 echo '</pre>';
 12 
 13 //result
 14 Array
 15 (
 16 [language] => php
 17 [db] => MySql
 18 [webserver] => Apache
 19 [os] => linux
 20 )
 21 Array
 22 (
 23 [os] => linux
 24 [webserver] => Apache
 25 [db] => MySql
 26 [language] => php
 27 )

二、统计数组元素的个数

1. array **array\_count\_values** ( array input)

//统计数组中所有值出现的次数,返回的依然是数组

1 $temp=array("os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "language"=>"php");
     2 
     3 $count=array_count_values($temp);
     4 
     5 print_r($count);
     6 
     7 
     8 //result
     9 
    10 Array ( [linux] => 1 [Apache] => 1 [MySql] => 1 [php] => 1 )

2. array **array\_unique** ( array array)  
//移除数组中重复的值

1 $temp=array("abc"=>"MySql", "os"=>"linux","webserver"=>"Apache", "db"=>"MySql", "language"=>"php");
    2 
    3 $count=array_unique($temp);
    4 
    5 print_r($count);
    6 
    7 //result
    8 
    9 Array ( [abc] => MySql [os] => linux [webserver] => Apache [language] => php )

三、使用回调函数处理数组的函数

1. array **array\_filter** ( array input \[, callback function\])

//回调函数过滤数组中的元素

**array\_filter()** 依次将 *input* 数组中的每个值传递到 *callback* 函数。如果 *callback* 函数返回 **TRUE**，则 *input* 数组的当前值会被包含在返回的结果数组中。数组的键名保留不变。

1 function ji($var){
     2     return ($var % 2 == 1);
     3 }
     4 function ou($var){
     5     return ($var % 2 == 0);
     6 }
     7 
     8 $array1 = array("a"=>1, "b"=>2, "c"=>3, "d"=>4, "e"=>5);
     9 $array2 = array(6, 7, 8, 9, 10, 11, 12);
    10 
    11 echo "jishu: ";
    12 print_r(array_filter($array1, "ji"));
    13 echo "oushu: ";
    14 print_r(array_filter($array2, "ou"));
    15 
    16 //result
    17 jishu: Array ( [a] => 1 [c] => 3 [e] => 5 ) oushu: Array ( [0] => 6 [2] => 8 [4] => 10 [6] => 12 )

2. bool **array\_walk** ( array array, callback function \[, mixed userdata\])  
//对数组中的每个成员应用用户函数,其中回调函数的第一个值为值，第二个为键，第三个为array\_walk的第三个参数

1 function guoyuan($value,$key){
 2 echo $key.'--is--'.$value.' '; 
 3 }
 4 function guoyuan1($value,$key,$class){
 5 echo $class.':'.$key."-is-".$value.' '; 
 6 }
 7 
 8 $fruits=array("a"=>"apple", "b"=>"banana", "p"=>"pear", "o"=>"orange");
 9 
 10 array_walk($fruits, "guoyuan");
 11 array_walk($fruits, "guoyuan1","fruits");
 12 
 13 //result
 14 a--is--apple
 15 b--is--banana
 16 p--is--pear
 17 o--is--orange
 18 fruits:a-is-apple
 19 fruits:b-is-banana
 20 fruits:p-is-pear
 21 fruits:o-is-orange

3. array **array\_map** ( mixed callback, array arr1 \[, array ...\])

//将回调函数作用到给定数组的单元上，返回的也是一个数组

function cube($value){
 return $value*$value*$value;
 }
 
 $num=array(1,2,3,4,5,6,7,8,9);
 
 $cube_num=array_map("cube",$num);
 echo '<pre>';
 print_r($cube_num);
 echo '</pre>';
 
 //result
 Array
 (
 [0] => 1
 [1] => 8
 [2] => 27
 [3] => 64
 [4] => 125
 [5] => 216
 [6] => 343
 [7] => 512
 [8] => 729
 )

可以传入多个数组，回调函数中参数的个数应该跟传入数组的个数一致

function test($first_n, $sec_n){
 return $first_n.'--is--'.$sec_n;
 }
 
 $num=array(1,2,3,4,5,6,7,8,9);
 $num_en=array("one", "two", "three", "four", "five", "six", "seven", "eight", "nine");
 
 $result=array_map("test", $num, $num_en);
 echo '<pre>';
 print_r($result);
 echo '</pre>';
 
 //result
 Array
 (
 [0] => 1--is--one
 [1] => 2--is--two
 [2] => 3--is--three
 [3] => 4--is--four
 [4] => 5--is--five
 [5] => 6--is--six
 [6] => 7--is--seven
 [7] => 8--is--eight
 [8] => 9--is--nine
 )

可以通过NULL构造一个数组的数组不用回调函数

$num=array(1,2,3,4,5,6,7,8,9);
 $num_en=array("one", "two", "three", "four", "five", "six", "seven", "eight", "nine");
 $num_2=array(11,22,33,44,55,66,77,88,99);
 
 $result=array_map(NULL, $num, $num_en, $num_2);
 echo '<pre>';
 print_r($result);
 echo '</pre>';
 
 //result
 Array
 (
 [0] => Array
 (
 [0] => 1
 [1] => one
 [2] => 11
 )
 
 [1] => Array
 (
 [0] => 2
 [1] => two
 [2] => 22
 )
 
 [2] => Array
 (
 [0] => 3
 [1] => three
 [2] => 33
 )
 
 [3] => Array
 (
 [0] => 4
 [1] => four
 [2] => 44
 )
 
 [4] => Array
 (
 [0] => 5
 [1] => five
 [2] => 55
 )
 
 [5] => Array
 (
 [0] => 6
 [1] => six
 [2] => 66
 )
 
 [6] => Array
 (
 [0] => 7
 [1] => seven
 [2] => 77
 )
 
 [7] => Array
 (
 [0] => 8
 [1] => eight
 [2] => 88
 )
 
 [8] => Array
 (
 [0] => 9
 [1] => nine
 [2] => 99
 )
 
 )

<完>

转载于:https://www.cnblogs.com/bukliu/p/php.html