validating a 7-digit phone number

[peppericious]

I know this should be easy.... However, to validate a 7-digit phone number, I wrote this:

 

<?php
if(!empty($_POST['mobile_number'])) {
          if(!is_numeric($_POST['mobile_number']) || strlen($_POST['mobile_number']) != 7) {
            $errors[] = 'Please enter a 7-digit number without spaces or dashes for your <strong>Mobile</strong>.';
          } else {
            $_SESSION['mobile_number'] = $_POST['mobile_number'];
          }
      } else {
        $_SESSION['mobile_number'] = '';
      }

 

... but now I realise that numeric/integer validation won't work because where I am - in Ireland - mobile numbers can start with an initial zero, too. So, the following mobile numbers are possible:

• 0123456
  
• 0224466
  

 

How can I ensure that:

[*]each digit in the mobile number is numeric

[*]an initial zero is possible

[*]there are exactly 7 digits

 

I suppose I loop through each digit, ensuring that that digit is numeric and break out of the loop if a non-numeric digit is encountered..?

Any suggestions?

 

TIA

[litebearer]

just a bleary-eyed thought...

$phone = trim($phone);
if(strlen($phone) !=7 OR preg_replace("/[^a-zA-Z0-9]/", "", $phone) !=$phone) {
/*  bad number */
}

[RussellReal]

or.. if you're going to use preg match anyway

 

<?php
if (preg_match('/^\d{7}$/',$number)) {
	// valid number
}
?>

[litebearer]

Russ, much better!!! Can you explain what the dollar sign indicates?

[RussellReal]

Russ, much better!!! Can you explain what the dollar sign indicates?

 

the ^ denotes start, and $ denotes end

 

if you're in multiline mode, ^ is the start of the string, and $ is the end of a string, however if you're not in multiline (dot all), then ^ is the start of a line, and $ is the end of a line..

 

so if you supply a string like:

 

'abc123'

 

a pattern like: '/.$/' will match '3'

 

Hope I helped!

 

Russell

[peppericious]

Thanks, guys. Excellent.

[RussellReal]

Anytime, can you mark as solved? Thanks!

[Pikachu2000]

There's no need for a regex pattern to do what you want to do. I'm not sure why you think a leading zero makes a difference. It shouldn't matter because all form values are sent as strings anyhow.

 

if( ctype_digit($number) && strlen($number) === 7 ) {
     // number is valid
}

[peppericious]

There's no need for a regex pattern to do what you want to do. I'm not sure why you think a leading zero makes a difference. It shouldn't matter because all form values are sent as strings anyhow.

 

if( ctype_digit($number) && strlen($number) === 7 ) {
     // number is valid
}

 

Yes, thanks, you're quite right.

 

In fact, I had defined the db fields as integers and consequently the leading zeroes were being truncated. When I changed the fields in the db to text, there was no further problem.

 

Thanks for showing me that ctype_digit function: useful to know in any case.