Understanding the Concept of Array_merge in PHP to the Core

Merging Two Simple Arrays

When the array_merge in PHP function is called for two more arrays, the values of one array are appended to the end of the previous array. When two elements have the same string key, the latter value takes precedence. Starting with zero, the integer keys will be renumbered. The array merge() function can be used to combine two arrays in the following way:

Example

<?PHP

$my_array1 = array("size" => "big", 2,3 );

$my_array2 = array("a", "b", "size" => "medium",

                        "shape" => "circle", 4);

$res = array_merge($my_array1, $my_array2);

print_r($res);

?>

Output

Passing Parameters

If the array merge() function is called with parameters and the array parameter's keys are an integer, the keys in the output array will be renumbered starting at 0 and increasing by 1 for each subsequent variable. The following example demonstrates this:

Example:

<?PHP

$my_array = array(1 => "This", 3=>"is", 2=>"Simplilearn");

$res = array_merge($my_array);

print_r($res); 

?>

Output:

Union Operator

The Union operator joins two array_merge in PHP together by appending the right-hand array to the left-hand array. If a key occurs in both arrays, the left-hand array's elements will be used, while the corresponding elements from the right-hand array will be ignored. The define() function is used to define constants in the following example.

Example

<?php

$arr1=array("phy"=>70, "che"=>80, "math"=>90);

$arr2=array("Eng"=>70, "Bio"=>80,"CompSci"=>90);

$arr3=$arr1+$arr2;

var_dump($arr3);

?> 

Output:

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Comparison of Arrays

When two arrays have the same key-value pairs, they are said to be identical. An indexed array and an associative array with keys corresponding to the index of elements in the first are used in the following example. As a result, both are equal.

Example

<?php

$arr1=array(0=>70, 2=>80, 1=>90);

$arr2=array(70,90,80);

var_dump ($arr1==$arr2);

var_dump ($arr2!=$arr1);

?>

Output:

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Conclusion

The array_merge in PHP function joins two or more arrays together. If the input arrays have matching string keys, the later value will take precedence over its predecessor. If the input array_merge in PHP contains numeric keys, the later value will be appended rather than overwritten. If there is only one array, it is numerically indexed, and the keys are continuously reindexed.

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