What is the function to synthesize arrays in php

There are three array composition functions: 1. array_combine(), which creates a new array by merging two arrays. The syntax is "array_combine (key name array, key value array)"; 2. array_merge(), which can To merge multiple arrays into one array, the syntax is "array_merge(array1,array2...)"; 3. array_merge_recursive(), which can merge multiple arrays into one array. The element key names will not be overwritten if they are the same. form subarrays.

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer

php provides 3 pairs of arrays for synthesis Function:

• array_combine()

• array_merge()

• array_merge_recursive()

1. Use array_combine() to synthesize arrays

array_combine() function creates a new array by merging two arrays, one of which is an array element. is the key name, and the elements of the other array are the key values.

array_combine(keys,values);

Note: The number of elements in the key name array and the key value array must be the same!

Example:

<?php
header("Content-type:text/html;charset=utf-8");
$name=array("Peter","Ben","Joe");
$age=array("35","37","43");
var_dump($name);
var_dump($age);
$arr=array_combine($name,$age);
var_dump($arr);
?>

2. Use the array_merge() function to synthesize an array

array_merge( ) function is used to combine one or more arrays into a single array.

Tip: You can input one or more arrays to the function.

array_merge(array1,array2,array3...)

Note: If two or more array elements have the same key name, the last element will overwrite the other elements.

Note: If you only input an array to the array_merge() function, and the keys are integers, the function will return a new array with integer keys, with keys re-indexed starting at 0 ( See Example 1 below).

Example:

<?php
header("Content-type:text/html;charset=utf-8");
$a1=array("a"=>"red","b"=>"green");
$a2=array("c"=>"blue","b"=>"yellow");
var_dump(array_merge($a1,$a2));
?>

3. Use array_merge_recursive() function

array_merge_recursive() function Used to combine one or more arrays into one array.

array_merge_recursive(array1,array2,array3...)

Explanation: The difference between the array_merge_recursive() function and the array_merge() function is to handle the situation where two or more array elements have the same key name. array_merge_recursive() does not perform key name overwriting, but recursively combines multiple values ​​with the same key name into an array.

Note: If you just input an array to the array_merge_recursive() function, the result is the same as array_merge(), the function will return a new array with integer keys, with keys starting at 0 for re-indexing.

Example:

<?php
header("Content-type:text/html;charset=utf-8");
$a1=array("a"=>"red","b"=>"green");
$a2=array("c"=>"blue","b"=>"yellow");
var_dump(array_merge_recursive($a1,$a2));
?>

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