title: Validate Mobile number in php form
body: <p>I want to validate mobile number of 10 digits and also add a prefix of 0 when I enter into the database.</p>
  
  <pre><code>&lt;?php
  
  include ('database_connection.php');
  
  $citystate = $_POST['citystate'];
  $serviceprovider = $_POST['serviceprovider'];
  $accept = $_POST['accept'];
  if (isset($_POST['formsubmitted'])) {
      $error = array(); //Declare An Array to store any error message 
  
      if (isset($_POST['checkbox'])) {
          $mumbai = (in_array("mumbai", $_POST['checkbox']) ? 1 : 0);
          $pune = (in_array("pune", $_POST['checkbox']) ? 1 : 0);
          $banglore = (in_array("banglore", $_POST['checkbox']) ? 1 : 0);
          $mysore = (in_array("mysore", $_POST['checkbox']) ? 1 : 0);
      }
  
      if ($mumbai + $pune + $banglore + $mysore == 0) {
          $error[] = 'Please check atleast one SMS center';
      }
  
      if ($accept != 1) {
          $error[] = 'Please check terms ';
      }
  
      if (empty($_POST['mobileno'])) {//if no name has been supplied 
          $error[] = 'Please Enter a Mobile Number '; //add to array "error"
      }
      if (empty($_POST['mobileno'])) {//if no name has been supplied 
          $error[] = 'Please Enter a Mobile Number '; //add to array "error"
      } else {
  
          $mobile = $_POST['mobileno']; //else assign it a variable
  
          /* if( preg_match("^[0-9]{10}", $mobile) ){
  
            }
  
            else {
  
            $error[] = 'Your Mobile No is invalid  ';
            } */
      }
      if (empty($_POST['fname'])) {//if no name has been supplied 
          $error[] = 'Please Enter a First name '; //add to array "error"
      } else {
          $fname = $_POST['fname']; //else assign it a variable
      }
  
      if (empty($_POST['lname'])) {//if no name has been supplied 
          $error[] = 'Please Enter a Last name '; //add to array "error"
      } else {
          $lname = $_POST['lname']; //else assign it a variable
      }
      if (empty($_POST['email'])) {
          $error[] = 'Please Enter your Email ';
      } else {
          if (preg_match("/^([a-zA-Z0-9])+([a-zA-Z0-9\._-])*@([a-zA-Z0-9_-])+([a-zA-Z0-9\._-]+)+$/", $_POST['email'])) {
              //regular expression for email validation
              $email = $_POST['email'];
          } else {
              $error[] = 'Your EMail Address is invalid  ';
          }
      }
  
  
      if (empty($_POST['passwd1'])) {
          $error[] = 'Please Enter Your Password ';
      } else {
          $password = $_POST['passwd1'];
      }
      if (empty($_POST['passwd2'])) {
          $error[] = 'Please Verify Your Password ';
      } else {
          $password = $_POST['passwd2'];
      }
      if ($_POST["passwd1"] != $_POST["passwd2"]) {
          $error[] = 'Password does not match';
      }
  
      if (empty($error)) { //send to Database if there's no error ' //If everything's OK...
          // Make sure the mobile no is available:
          $query_verify_mobileno = "SELECT * FROM userdtls WHERE mobileno = '$mobile'";
          $result_verify_mobileno = mysqli_query($dbc, $query_verify_mobileno);
          if (!$result_verify_mobileno) {//if the Query Failed ,similar to if($result_verify_mobileno==false)
              echo ' Database Error Occured ';
          }
  
          if (mysqli_num_rows($result_verify_mobileno) == 0) { // IF no previous user is using this number .
              // Create a unique  activation code:
              //$activation = md5(uniqid(rand(), true));
              $query_insert_user = "INSERT INTO userdtls ( mobileno, serviceprovider, pass,  fname, lname, email, citystate, MUM, PUN, BNG, MYS ) VALUES ( '" . $mobile . "', '" . $serviceprovider . "', '" . $password . "', '" . $fname . "', '" . $lname . "', '" . $email . "', '" . $citystate . "','" . $mumbai . "', '" . $pune . "', '" . $banglore . "', '" . $mysore . "'  )";
          }
      }
  }
  </code></pre>
  
  <p>Now I get stuck in mobile number validation. I tried using regular expressions. </p>
  
  <p>What I want to do is add a 10 digit phone number and make sure it is only digits or else give error and while entering the number to database I want to add a prefix to the mobile number of 0 so it should be like 0and10digitnumber</p>