PHP obtains the value set of a column in a two-dimensional array. _ PHP Tutorial-php Tutorial

PHP obtains the value set of a column in a two-dimensional array ,. PHP obtains the value set of a column in a two-dimensional array, which is commonly used by PHP. so I studied the two-dimensional array of PHP. When processing php arrays, there is a special need. for example, PHP obtains the value set of a column in a two-dimensional array,

PHP is still quite common, so I studied the two-dimensional PHP array. When processing php arrays, the following two-dimensional arrays are frequently required:

$ Arr = array (1 => array ('id' => 5, 'name' => 'Zhang San'), 2 => array ('id' => 6, 'name' => 'Lily '));

The purpose is to obtain the set with key as name and get the result:

$ Arr2 = array (0 => 'Zhang San', 1 => 'Li si ');

There are several methods:

1: The simplest, foreach traversing the array:

foreach ($arr as $key => $value) {$arr2[] = $value['name'];}

2: The php method of array_map is used for a slightly less code:

$arr2 = array_map('array_shift',$arr);

Remove the value starting with each item of the $ arr array and return the value to be removed from each item, note that the key of the new array $ arr2 is still the key of the original array $ arr.

2.1: on the basis of Method 2, you can slightly open the brain hole. if you need to obtain the starting or ending columns of each item in a two-dimensional array, you can also do this:

$arr2 = array_map('reset',$arr);$arr2 = array_map('end',$arr);

Haha, it's very convenient.

3: You can also use the array_reduc e method, but the code is slightly larger. However, the imagination of this method (for other array value operations) is quite large:

$arr2 = array_reduce($arr, create_function('$result, $v', '$result[] = $v["name"];return $result;'));

The array_reduce method uses the callback function to iterate over the value of the array. create_function is used for an anonymous method to call back. The parameter $ result of this anonymous method is the value generated in the previous iteration, $ v is the current value. The internal implementation is to get the "name" value of each $ arr item and push it to the new $ result array;

4: In the end, this ultimate method is really cool. it can be done with one method, and it is very flexible:

$arr2 = array_column($arr, 'name');

The second parameter is the key name of the column to be obtained. is it very convenient? However, this method has a limit that the php version must be> = 5.5.0, to use this method in outdated projects, consider it.

PS: several methods for traversing two-dimensional arrays in php

<? Php // use for loop traversal $ arr2 = array ("zhang san", "20", "male"), array ("Li Si", "25 ", "Male"), array ("Wang Wu", "19", "female"), array ("Zhao Liu", "25", "female"); echo"

 
 "; For ($ I = 0; $ I <4; $ I ++) {echo" 
   
     "; For ($ j = 0; $ j <3; $ j ++) {echo" 
    ";} Echo" 
   "; Echo"";} Echo" 
  

  
  
 
   
 
    
Name
 
    
AgeGender
 
   
"; Echo $ arr2 [$ I] [$ j]; echo"
 
 
";?> // Use foreach to traverse <? Php $ arr = array ('one' => array ('name' => 'Zhang San', 'age' => '23 ', 'Sex' => 'male'), 'two' => array ('name' => 'Lily', 'age' => '43 ', 'Sex' => 'female '), 'Three' => array ('name' => '王', 'age' => '32 ', 'Sex' => 'male'), 'Four '=> array ('name' => 'Zhao Liu', 'age' => '12 ', 'Sex' => 'female '); foreach ($ arr as $ k => $ val) {echo $ val ['name']. $ val ['age']. $ val ['sex']."
";} Echo"
";?> <? Php $ arr = array ('one' => array ('name' => 'Zhang San', 'age' => '23 ', 'Sex' => 'male'), 'two' => array ('name' => 'Lily', 'age' => '43 ', 'Sex' => 'female '), 'Three' => array ('name' => '王', 'age' => '32 ', 'Sex' => 'male'), 'Four '=> array ('name' => 'Zhao Liu', 'age' => '12 ', 'Sex' => 'female '); foreach ($ arr as $ key => $ value) {foreach ($ value as $ key2 => $ value2) {echo $ value2;} echo"
";}?>

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