isdigit(3)                                                   isdigit(3)

  isdigit()

  NAME

    isdigit() - decimal-digit character test

  SYNOPSIS

    #include 

    int isdigit (int c)

  DESCRIPTION

    The isdigit(3) function tests whether c is a character of class digit in
    the program's current locale.

    In the POSIX locale, the character class digit includes only the
    characters:

    0 1 2 3 4 5 6 7 8 9

  RETURN VALUES

    The isdigit(3) function returns zero if the character tests false and
    returns non-zero if the character tests true.

  SEE ALSO

    isalnum(3)

    isalpha(3)

    isblank(3)

    iscntrl(3)

    isgraph(3)

    islower(3)

    isprint(3)

    ispunct(3)

    isspace(3)

    isupper(3)

    isxdigit(3)

    tolower(3)

    toupper(3)

  USAGE NOTES

    The isdigit function is thread safe.

    The isdigit function is not async-signal safe.