Why your regex matches the string can be explained like this:
"(?=hello)" matches "hello"
".*" matches "hello Ga"
"[^G]" matches "g"
"[^a]" matches "s"
".*" matches nothing
Your regex properly skips matching [^G][^a] with "Ga" but will happily match stuff after that.
You probably want to do something like this with a negative look ahead:
( "hello Gags" =~ /^(?=hello)(?!.*Ga/ )&& print ("Matched") || print (
+"Unmatched")
Update
To answer your question about how debugging, I find that throwing in a few capturing parens, can often help you to see what is being matched. Here is is a simple example:
use strict;
( "hello Gags" =~ /^(?=hello)(.*)([^G][^a])(.*)$/ ) ? matches() : pri
+nt ("Unmatched");
sub matches {
no strict 'refs';
for (1..10) {
my $tmp = ${$_} or next;
print "\$$_ = '$tmp'\n";
}
return 1;
}
__OUTPUT__
$1 = 'hello Ga'
$2 = 'gs'
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