Hi, jmclark -

The question you ask is, I think, one that everyone working with regular expressions has at some stage. As GrandFather already explained, the problem is due to the behaviour of Perl's regular expression engine.
The normal and idiomatic way to avoid this kind of undesired interference of the match position would be to write the checks for regular expression match as follows: 
$gw="abcdefgh";
if ( ( my $a = $gw ) =~ m/abc/ig){
    print pos( $a ), ": abc\n";
}
if ( ( my $b = $gw ) =~ m/cde/ig){
    print pos( $b ), ": cde\n";
}
if ( ( my $c = $gw ) =~ m/defgh/ig){
    print pos( $c ), ": defgh\n";
}
if ( ( my $d = $gw ) =~ m/gh/ig){
    print pos( $d ), ": gh\n";
}
if ( ( my $e = $gw ) =~ m/fg/ig){
    print pos( $e ), ": fg\n";
}

[download]
Effectively, you are thus copying the contents of $gw into the variables $a, $b ... and are not directly checking for the match of $gw anymore. This approach will then return what you had initially expected: 
3: abc
5: cde
8: defgh
8: gh
7: fg

[download]
Hope this helps.

Regards -

Pat

In reply to Re: Multiple if statements matching part of one variable problem by pat_mc
in thread Multiple if statements matching part of one variable problem by jmclark

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