PHP encoding to only have letters and numbers

Question

Is there a encoding function in PHP which will encode strings and the resulting output will only contain letters and numbers? I would use base64 but that still has some stuff which is not numeric/alphanumeric

Answer 1

You could use base32 (code easy to google), which is sort of a standard alternative to base64. Or resort to bin2hex() and pack("H*",$hex) to reverse. Hex encoding however leads to size doubling.