Detailed explanation of method examples of php merging arrays according to classification_PHP tutorial

For the simplest array merging, we only need to use array_merge
array_merge() merges the cells of two or more arrays, and the values ​​in one array are appended to the previous array. Returns the resulting array.
When the array key name is a numeric key name, and the two arrays to be merged have numeric KEYs with the same name, using array_merge() will not overwrite the original value, while using "+" to merge the arrays will replace the first The value that appears is returned as the final result, and those values ​​in subsequent arrays with the same key name are "discarded" (note: the value that appears first is not overwritten but retained). Example:

Copy code The code is as follows:

$array1 = array(1=>'0');
$array2 = array(1=> "data");
$result1 = $array2 + $array1;/*The result is the value of $array2*/
print_r($result);
$ result = $array1 + $array2 ;/*The result is the value of $array1*/
  print_r($result);
  $result3 = array_merge($array2,$array1);/*The result is $array2 and $ The value of array1, the key name is reassigned*/
​​​​​print_r($result3); Re-allocate*/
print_r($result4);

The output result is:
Array ( [1] => data )
Array ( [1] => 0 )
Array (
[0] => data
[1] => 0
)
Array
(
[0] => 0
[1] => data
)

2. When the same array key name is a character, the "+" operator is the same as when the key name is a number, but array_merge() will Overwrite the previous value with the same key name.
Example:

Copy code The code is as follows:

$array1 = array('asd'=>'0 ');
$array2 = array('asd' => "data");
$result1 = $array2 + $array1;/*The result is the value of $array2*/
print_r($ result);
$result = $array1 + $array2 ;/*The result is the value of $array1*/
print_r($result);
$result3 = array_merge($array2,$array1);/ *The result is $array1*/
print_r($result3);
$result4 = array_merge($array1,$array2);/*The result is $array2*/
print_r($result4);

The output result is:
Array ( [asd] => data )
Array ( [asd] => 0 )
Array ( [asd] => 0 )
Array ( [asd] => data )

After talking so much, here is what I want to introduce to my friends
Array reorganization based on classification fields

Copy code The code is as follows:

//Array that needs to be reorganized
$arrar=array();
$array[]=array('ItemID' => 110126866896,'CategoryID'=>111);
$array[]=array('ItemID' => 120126866896,'CategoryID'=> 112);
$array[]=array('ItemID' => 130126866896,'CategoryID'=>113);
$array[]=array('ItemID' => 140126866896,'CategoryID '=>114);
$array[]=array('ItemID' => 150126866896,'CategoryID'=>115);
$array[]=array('ItemID' => 160126866896,'CategoryID'=>116);
$array[]=array('ItemID' => 170126866896,'CategoryID'=>117);
$array[]=array('ItemID ' => 118126866896,'CategoryID'=>111);
$array[]=array('ItemID' => 121126866896,'CategoryID'=>112);
$array[]= array('ItemID' => 132126866896,'CategoryID'=>113);
$array[]=array('ItemID' => 143126866896,'CategoryID'=>114);
$ array[]=array('ItemID' => 154126866896,'CategoryID'=>115);
$array[]=array('ItemID' => 165126866896,'CategoryID'=>116);
$array[]=array('ItemID' => 176126866896,'CategoryID'=>117);
//The array is reorganized according to classification
$newArray=array();
foreach($array as $val){
$newArray[$val['CategoryID']][]=$val;
}

//Delete the original array to free up space
$ array=null;
unset($array);

print_r($newArray);

?>

http://www.bkjia.com/PHPjc/825097.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/825097.htmlTechArticleThe simplest array merging, we only need to use array_merge array_merge() to merge the cells of two or more arrays Together, the values ​​in one array are appended to the previous array. Return...