PHP gets a collection of values for a column in a two-dimensional array, _php tutorial

PHP gets a collection of values for a column in a two-dimensional array,

PHP is still more commonly used, so I studied php two-dimensional array. In the process of working with PHP arrays, there is a particular need for frequent, two-dimensional arrays such as:

$arr = Array (1=>array (' id ' = = 5, ' name ' = ' Zhang San '), 2=>array (' id ' = = 6, ' name ' = ' John Doe '));

The goal is to take the key to the name collection and get this result:

$arr 2 = Array (0=> ' Zhang San ',1=> ' John Doe ');

Here are a few ways:

1: The simplest, foreach traversal array:

foreach ($arr as $key = + $value) {$arr 2[] = $value [' name '];}

2: Code a bit less code, using Array_map this PHP method:

$arr 2 = array_map (' Array_shift ', $arr);

Remove the value from the beginning of each value of the $arr array and return the value that was moved out of each item value, noting 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 open a little bit of the brain hole, if you need to get a two-dimensional array of each item of the beginning column or the end column, you can also do this:

$arr 2 = array_map (' Reset ', $arr); $arr 2 = Array_map (' End ', $arr);

Haha, is also very convenient

3: You can also use the Array_reduc E method, but the code is slightly more, but this method of the imaginary space (for other array value operation) is still quite large:

$arr 2 = array_reduce ($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, and create_function is used for an anonymous method to call back, the parameter of the anonymous method $result the value generated for the last iteration, $v is the current value, and the internal implementation is both getting to the array $ The value of "name" for each entry of ARR and push to the new $result array;

4: Finally the ultimate method is really cool, a method is done, and very flexible:

$arr 2 = array_column ($arr, ' name ');

The second parameter is the key name of the column you want to get, is not very convenient, but this method has a limitation, that is, PHP version must be >= 5.5.0, use this method in a stale project you have to think about it.

Several ways of traversing two-dimensional arrays in ps:php

<?php//uses the For loop to traverse $arr2=array (Array ("Zhang San", "20", "male"), Array ("John Doe", "25", "male"), Array ("Harry", "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
 
    
Age Sex
 
   
"; echo $arr 2[$i [$j]; echo "

 
 
";? >//uses a foreach traversal <?php$arr = Array (' One ' =>array (' name ' = ' = ' Zhang San ', ' age ' = ' ' ", ' sex ' = ' male '), ' one '" = Array (' name ' = ' = ' John Doe ', ' age ' = ' + ', ' sex ' = ' female '), ' three ' =>array (' name ' = ' = ' Harry ', ' age ' = ' + ', ' sex ' = > ' Male '), ' Four ' =>array (' name ' = ' Zhao Liu ', ' age ' = ' + ', ' sex ' = ' female '); foreach ($arr as $k + $val) {echo $val [' Name ']. $val [' age ']. $val [' sex ']. "
";} echo "
";? ><?php$arr = Array (' One ' =>array (' name ' = ' = ' Zhang San ', ' age ' = ' ~ ', ' sex ' = ' male '), ' One ' =>array (' name ' = > ' John Doe ', ' age ' = ' + ', ' sex ' = ' female ', ' three ' =>array (' name ' = ' Harry ', ' age ' = ' + ', ' sex ' = ' male '), ' four ' = >array (' name ' = ' Zhao Liu ', ' age ' = ' + ', ' sex ' = ' female '); foreach ($arr as $key = + $value) {foreach ($value as $key 2 = > $value 2) {echo $value 2;} echo "
";}? >

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