string base_convert (string number, int frombase, int tobase)
Returns a string containing number represented in base tobase. The base in which number is given is specified in frombase. Both frombase and tobase have to be between 2 and 36, inclusive. Digits in numbers with a base higher than 10 will be represented with the letters a-z, with a meaning 10, b meaning 11 and z meaning 35.
Example 1. Base_convert()
$binary = base_convert ($hexadecimal, 16, 2);