in reply to Re: uninitialized value in phonebook program
in thread uninitialized value in phonebook program

when you change the code to print out the values of $name, $1, and $2: 
foreach $name (keys %book) {   #write the data
    print "$name \n";
    $name =~ /(.+)&(.+)/;
    print "$1, $2 \n";
    if ($2 =~ /^0$/) {
        print BOOK "$1,::";
    } else {
        print BOOK"$1,$2::";
    }
    for ( 0 .. $#{ $book{$name} } ) {
         print BOOK $def[$_+2] . ":" . $book{$name}[$_] . "::" unless 
+$book{$name}[$_] =~ /^0$/;
    }
    print BOOK "\n";
}

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you get the correct output, and it shows $1 and $2 are initialized, but you still get the uninitialized error. Here is the output when you pass it School&0 and one number: 

school&0

school, 0 
# Use of uninitialized value, <> chunk 7.
File 'untitled:Desktop Folder:Will's Stuff:Applications:MacPerl ƒ:phonebook'; Line 57
so that isnt the problem. Loop lables are a good idea, though, thanks

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Re: Re: Re: uninitialized value in phonebook program
by chipmunk (Parson) on Feb 25, 2002 at 05:09 UTC
    Oh, now I got it! The warning is not actually coming from the if ($2 =~ /^0$/) { line. Unfortunately, perl sometimes reports the line number where an if block starts when the warning actually occurs later in the block. That's what is happening here.

    First, you perform a regex match against $name, setting $1 and $2. Then, you perform a regex match against $2. So far, so good. Then you print out the values of $1 and $2. Oops! That second regex match you just did has wiped out the values of $1 and $2!

    jeffa's node shows two ways to solve this problem. Either assign the results of the first match to new variables: my($first, $last) = $name =~ /(.+)&(.+)/; Or replace the second match with a comparison: if ($2 eq '0') {

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