Please test it before giving me the solution.

Is this another "please do the work for me" thing? If you want good answers, a nice way is to provide the testing code yourself, so that people just need to plug in their regexes.

Anyway, my approach would be /^(?!.*, $)/

mohamedrabeek:

Hint: It would be easy to match all other lines. You can get that one, right?

If not....

...roboticus

Show what you used so we can help you learn why it did not work. The code below shows a working solution. It is not very elegant but it does work:

$line1 = "this is an example";
$line2 = "this is another example,";
$line3 = "this is yet another example    ";
$line4 = "despite what you think this is not an example,    ";

if ($line1 !~ /.*,\s*$/)
{
    print "MATCHED : $line1\n";
}
else 
{
    print "MISMATCH: $line1\n";
}
# ... repeated for $line2 $line3 and $line 4
##########################################################
# Output         
#MATCHED : this is an example
#MISMATCH: this is another example,
#MATCHED : this is yet another example
#MISMATCH: despite what you think this is not an example,
##########################################################
[download]

Like this?

while (<DATA>) {    
    if (!/,\s+$/) {
        print;
    }
}

__DATA__
1) this is an example 
2) this is an example, 
3) this is an example,
4) this is an example
[download]

/^[^,]*(?:,\s*[^\s,][^,]*)*$/
[download]