Any way that to cut only number or char from the string in php

[zym120]

Does anyone know how can I cut only number or char from the string in php?Example\[code\]$test = '12b';\[/code\]any way that I can only cut the number from the variable: 12?also and way that I can only cut out the char: b? NOTE: the $test string flexible to changed.. means it could come with '123b', '1a'...