PHP Code
<?php
if(isset($_POST['submit']))
{
$str="https://wa.me/+91-9795000000?text=";
$str.="Roll%20:%20" . preg_replace('/ /','%20',$_POST['Roll']);
$str.= ",Name%20:%20" . preg_replace('/ /','%20',$_POST['Name']);
$str.=",City%20:%20" . preg_replace('/ /','%20',$_POST['City']);
header("Location: $str");
}
?>
HTML
<form method="post" style="margin:4%">
<input type="text" name="Roll" /><br />
<input type="text" name="Name" /><br />
<input type="text" name="City" /><br />
<input type="submit" name="submit" value="Send" />
</form>