Adding array to an existing array by using array

We can add array ( one or more ) to an existing array by using array_merge function in PHP. By this two arrays can be joined and one resulting array can be generated.

$result = array_merge($array1, $array2,...);

We will try with an example.

Example with two arrays

$first=array('a','b','c','d','e');
$second=array('f','g','h');
$result=array_merge($first,$second);
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

Output is here

0 -> a 
1 -> b 
2 -> c 
3 -> d 
4 -> e 
5 -> f 
6 -> g 
7 -> h

With some common elements

$first=array('a','b','c','d','e');
$second=array('h','d','b','f'); //with some common elements 
$result=array_merge($first,$second);
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

Output is here

0 -> a 
1 -> b 
2 -> c 
3 -> d 
4 -> e 
5 -> h 
6 -> d 
7 -> b 
8 -> f

With numeric keys

We can preserve the keys of the first array.

$first=array(1=>'First',2=>'Second',3=>'Third');
$second=array(1=>'fourth',2=>'Fifth',3=>'Sixth');

$result=array_merge($first,$second);

while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

The output is here.

0 -> First 
1 -> Second 
2 -> Third 
3 -> fourth 
4 -> Fifth 
5 -> Sixth

Keys are renumbered and incremented starting from 0.

associative array with literal keys

$first=array('Fruits1' =>'Banana','Fruits2'=>'Mango','Fruits3'=>'Apple');
$second=array('new_fruit1'=> 'Strawberry','new_fruit2'=>'Grapes');
$result=array_merge($first,$second);
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

Output is here

Fruits1 -> Banana 
Fruits2 -> Mango 
Fruits3 -> Apple 
new_fruit1 -> Strawberry 
new_fruit2 -> Grapes

With common literal keys

$first=array('Fruits1' =>'Banana','Fruits2'=>'Mango','Fruits3'=>'Apple');
$second=array('Fruits1'=> 'Strawberry','Fruits2'=>'Grapes');
$result=array_merge($first,$second);
while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

Output is here

Fruits1 -> Strawberry 
Fruits2 -> Grapes 
Fruits3 -> Apple

Keys of the first array will be retained.

Adding by union of two arrays ( Using operand + )

We can add two arrays by using union command like this .

$result=$first + $second;

If we use this in place of array_merge() ( in above code ) then the output will be like this

1 -> First 
2 -> Second 
3 -> Third

Let us change the second array and see the result.

$first=array(1=>'First',2=>'Second',3=>'Third');
$second=array(4=>'fourth',5=>'Fifth',6=>'Sixth');

$result=$first + $second;

while (list ($key, $val) = each ($result)) {
echo "$key -> $val <br>";
}

Output is here

1 -> First 
2 -> Second 
3 -> Third 
4 -> fourth 
5 -> Fifth 
6 -> Sixth

You can read more array Operators.

When to use array_merge and array_push

We will be using array_merge when we want to add one array to an existing array. But to add elements to an existing array we will be using array_push function in PHP
Difference of two arrays by array_diff
Array REFERENCE

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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