Replacing Spaces with Underscores

Question

I have a PHP Script that users will enter a name like: Alex_Newton,

However, some users will use a space rather than an underscore, so my question is:

Answer 1

You can also do this to prevent the words from beginning or ending with underscores like _words_more_words_, This would avoid beginning and ending with white spaces.

$trimmed = trim($string); // Trims both ends
$convert = str_replace('', '_', $trimmed);