Need help, Please help me!

[WapAdda]

Im using a service. Dat service data save at myservice.txt file. Service field r 1.name 2.country 3.mobile no.

Now, how to stop same data submiting by user.

Or, how to show user name already exits! Go back & write another name.

[something else]

<?php
$filename = "myservice.txt";
$handle = fopen($filename, "r");
$contents = fread($handle, filesize($filename));
fclose($handle);
if(substr_count($contents,$_POST['name'])>0){
print "name already registered";
}else{
print "name doesnt exsist";
}
?>

[WapAdda]

<?php
$filename = "myservice.txt";
$handle = fopen($filename, "r");
$contents = fread($handle, filesize($filename));
fclose($handle);
if(substr_count($contents,$_POST['name'])>0){
print "name already registered";
}else{
print "name doesnt exsist";
}
?>

thank u sir, dis code really working..