指定字段中的整数数

Question

I'm doing a sign up form page where I should put also a "telephone" input but i need the telephone field to be 8 digits!!! if a user put a number more or less than 8 digits the signup form tells him an error.

it should be like this i think... after connecting to DB

  $telephone=$_POST['telephone'];
  ... 
  .... 
  if(empty($telephone)){ // **i think i should write smth here???**
  echo  "phone number not set, and should be 8 digits!!" ;
  }
  else{

  /* Now we will write a query to insert user details into database */
  $insert_user=mysql_query("INSERT INTO login (telephone) VALUES ('$telephone')");

i appreciate any help :) thank you

Answer 1

First of all: not all telephone numbers are exactly 8 digits. So you shouldn't force it that strictly.

For sensible validation of phone numbers, there are a number of good answers in this thread: A comprehensive regex for phone number validation

On a personal note, you really shouldn't use more than one exclamation mark in production code. Reading a '!!' is somewhat... upsetting... to users and other developers alike.