On 2/8/10 Mon Feb 8, 2010 4:56 PM, "Chris Coggins" <cacogg...@cox.net>
scribbled:
> What is the proper syntax for a comparison at the end of a subroutine to
> stop the script if a certain variable is "0" or ''?
>
> sub routine{
> (get data and process it)
> if $varA = '' || $varA = "0" {
> (stop script, print error message to user)
> }
> else{
> (continue with script)
> }
The scalar values '' and 0 (not in quotes) are 2 of the 3 logically false
scalar values. (The undef value is the third, and an empty array is
another.) If you can accept stopping your program if $varA is undef as well
as '' or 0, then you can simply test the logical value of $varA:
if( $varA ) {
# continue with program
}else{
exit(0); # stop program
}
You can use 'unless' instead of 'if' and swap blocks:
unless( $varA ) {
exit(0);
}else{
# continue with program
}
Since exit does not return, you can shorten this:
unless( $varA ) {
exit(0);
}
Or shorten again:
exit(0) unless $varA;
You can use print() to print a message before terminating. You can also use
die(), which will print its argument and terminate the program:
die("The variable \$varA does not have a valid value") unless $varA;
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