[PHP array implode explode] #php

phpimpexp.txt

To convert array items into a comma-separated string, use the implode() function:

$skills = array( 'html', 'css', 'js', 'php' );
$comma_separated = implode(',', $array);
echo $comma_separated; // output: html,css,js,php

You can also convert a string to an array using the explode() function:
$skills = 'html css js php';
$skills_array = explode( ' ', $skills );
print_r( $skills_array );
// output: Array ( [0] => html [1] => css [2] => js [3] => php