I already found a solution with loops, so this question is only to refresh my memory: Is there a function which removes all alphabetical characters from a string?
"32c" -> "32"
"123.5 cm" -> "123.5"
"- 12.3" -> "-12.3"
"x 28" -> "28"
I don't have much hope, because it should not remove "-".
Maybe better to use my loop ..
EDIT: I edited now "characters" to "alphabetical characters".