What is the purpose of the join function in PHP?

The PHP join() function is used to combine array elements into a string, separating each element with a specified separator. Its syntax is:

string join(string $separator, array $array)

The $separator parameter is the separator used to separate the array elements, by default it is an empty string; the $array parameter is the array to be combined.

“I’ll never forget the day we met.”
“I will always remember the day we first met.”

$array = array('Hello', 'World', 'PHP');
$string = join(' ', $array);
echo $string; // 输出: Hello World PHP

Please note that the join() function is equivalent to the implode() function, meaning that the join() function is an alias for implode().