How to check a variable content if only digits in Perl?

if ($a =~m/\D) {
  # here be it having non-digits
} else {
  # here be digits only
}
Pretty sure that's right...

Oops, syntax error there...
Make that:

if ($a =~ m/\D/) {

From the Perl FAQ

   How do I determine whether a scalar is a number/whole/integer/float?
       Assuming that you don't care about IEEE notations like "NaN" or "Infinity", you probably just want to use a regular
       expression.

               if (/\D/)            { print "has nondigits\n" }
               if (/^\d+$/)         { print "is a whole number\n" }
               if (/^-?\d+$/)       { print "is an integer\n" }
               if (/^[+-]?\d+$/)    { print "is a +/- integer\n" }
               if (/^-?\d+\.?\d*$/) { print "is a real number\n" }
               if (/^-?(?:\d+(?:\.\d*)?|\.\d+)$/) { print "is a decimal number\n" }
               if (/^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/)
                               { print "a C float\n" }

       There are also some commonly used modules for the task.  Scalar::Util (distributed with 5.8) provides access to perl's
       internal function "looks_like_number" for determining whether a variable looks like a number.  Data::Types exports
       functions that validate data types using both the above and other regular expressions. Thirdly, there is
       "Regexp::Common" which has regular expressions to match various types of numbers. Those three modules are available
       from the CPAN.

       If you're on a POSIX system, Perl supports the "POSIX::strtod" function.  Its semantics are somewhat cumbersome, so
       here's a "getnum" wrapper function for more convenient access.  This function takes a string and returns the number it
       found, or "undef" for input that isn't a C float.  The "is_numeric" function is a front end to "getnum" if you just
       want to say, "Is this a float?"

               sub getnum {
                       use POSIX qw(strtod);
                       my $str = shift;
                       $str =~ s/^\s+//;
                       $str =~ s/\s+$//;
                       $! = 0;
                       my($num, $unparsed) = strtod($str);
                       if (($str eq '') || ($unparsed != 0) || $!) {
                                       return undef;
                               }
                       else {
                               return $num;
                               }
                       }

               sub is_numeric { defined getnum($_[0]) }

       Or you could check out the String::Scanf module on the CPAN instead. The "POSIX" module (part of the standard Perl
       distribution) provides the "strtod" and "strtol" for converting strings to double and longs, respectively.

@dagesi:

How can I make digits only  in IF and non-digtis in ELSE using this method?

Thanks,

>Tolgar...
I think it would be:

if ($a !~ m/\D) {
  # here be it having digits
} else {
  # here be non-digits only
}

Word of warning... if you try these, be sure to test using a totally blank variable - I'm not positive which set that would fall into.

Well, these back and forth slashes make the code little weird. It changes the rest of the code in terms of variable declarations and so on. I can even see it before compiling by looking at the color on emacs.

How can I fix it?

 I tried to put // but it did not work.

Thanks,