public $phonenumber = "90XXXXXX90"; function setphonenumber($phonenumber) { if (isphonenumber($phonenumber)) { $this->phonenumber = $phonenumber; } else { echo "please provide valid phpone number"; } } } class guest extends person { public $indianphonenumber = ""; function setindianphonenumber($phonenumber) { if (isphonenumber($phonenumber . '0')) { $this->indianphonenumber = $phonenumber; } else { echo "please provide a valid phone number"; } } } $indian = new guest(); $indian->name = "Daniel"; $indian->email = "*****@*****.**"; $indian->setindianphonenumber("8008900910"); $indian->setphonenumber("8008900910"); echo $indian->name, "<br>"; echo $indian->email, "<br>"; echo $indian->phonenumber, "<br>"; echo $indian->indianphonenumber, "<br>";