how to merge two key value array to one key valie in php code example

Example 1: array merge in php

/* Array merge is basically use to merge the two array data. */
  
<?php
$a1=array("red","green");
$a2=array("blue","green","yellow");
print_r(array_merge($a1,$a2));
?>
  
/*
Output:
Array ( [0] => red [1] => green [2] => blue [3] => green [4] => yellow )
*/
  
<?php
$a1=array("a"=>"red","b"=>"green");
$a2=array("c"=>"blue","b"=>"yellow");
print_r(array_merge($a1,$a2));
?>

/*
Output:
Array ( [a] => red [b] => yellow [c] => blue )
*/
  
/* In above example you can check the difference in output 
it takes all values of both array in final output, but not in associative array you can check.
because one value gets overwritten by same key reference in both array.
*/

Example 2: php join array

Definition and Usage
The join() function returns a string from the elements of an array.

The join() function is an alias of the implode() function.

Note: The join() function accept its parameters in either order. However, for consistency with explode(), you should use the documented order of arguments.

Note: The separator parameter of join() is optional. However, it is recommended to always use two parameters for backwards compatibility.

Syntax
join(separator,array)
  
Example
Join array elements with a string:

<?php
$arr = array('Hello','World!','Beautiful','Day!');
echo join(" ",$arr);
?>
  
Output:
Hello World! Beautiful Day!