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 /^(?!.*, $)/

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]

mohamedrabeek:

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

If not....

...roboticus

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]