- SYNOPSIS
-
Tests if a one-character string is a decimal digit.
- DESCRIPTION
-
The call isnum s tests whether the first character of string s (normally
it is the only character) is a decimal digit.
- FAILURE CONDITIONS
-
Fails if the string is empty.
- SEE ALSO
-
isalnum, isalpha, isbra, issep, isspace, issymb.