How to determine if a string is numeric in ksh

Question

I'm trying to validate input in ksh, and would like to know the easiest way to determine if a string is a valid number.

Answer 1

Have a go with :

    case $INPUT in
        +([0-9])*(.)*([0-9]) )
              # Variable is numeric
              ;;
        *) 
              # Nope, not numeric
              ;;

esac