Validate Mobile number in php form

Question

I want to validate mobile number of 10 digits and also add a prefix of 0 when I enter into the database.

Answer 1

For Indian Mobile Numbers it will be easiest

if(is_numeric($num)){
if($num>=1000000000 && $num<=9999999999){
$num="0".$num;
}
else{
echo "Invalid Mobile Number";
}
}
else{
echo "Hey Buddy mobile numbers are always in digits";
}

This idea struck me because of the willingness of finding easy and some short of mind because the number(1000000000 ) is the lowest numerical value(10 digits) and the number (9999999999) is a highest numerical value that can be used as a mobile number in India. And one more thing code will run faster than other solutions.