$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,
##########################################################