Couple Perl questions

[Jason Berendsen]

Hello,

I am trying to find a way to find if a variable is numeric. Does anyone know how the isnum function works? Do you need to define a library to use it? Is there another way to do this.

Also, is there an equivalent to the ksh $? in Perl for the return code of a command?

Thanks,

Jason

[Jordan Bean]

In PERL, $? is also known as $CHILD_ERROR. It holds the error value of the last `cmd`, pipe close, wait, waitpid, or system function.

Also at your disposal is $@ ($EVAL_ERROR) which is the error value for the last eval or do expression.

I am not aware of any such implicit variable that holds the error value of the last PERL internal function.

[Rodney Hills · Accepted solution]

In perl to test for number, one way is

if ($x=~/^\d+$/) {
print "it is a number\n";
} else {
print "not a number\n";
}

-- Rod Hills

[H.Merijn Brand (procura]

If something is a number is much more complicated than Rodney shows. Think about fractionals and exponents. The FAQ show a complete example of a complicated regex that can deal with all.

If it is digits only, you could (more safely) do

m/^\s*\d+\s*$/; # strip leading and trailing spaces

Jordan, the long names are *only* available under 'use English'. Use $? and $! after simple system interaction, and $@ after eval