- source is the original to encode
Returns the encoded version of the supplied source string with all non-alphanumeric characters replaced with the standard URI-encoded escape sequences. For example, spaces are replaced with "+" and other special characters are replaced by "%" followed by a two-digit (hexadecimal) character code.
See the w3c page here for more info.
String converted by this function can be returned to their original form with url_decode().