Question

Possible Duplicate:
php regex , extract phone number from text/html

I have following requirement. There is a phone number field.

• Its length should be between 8 and 10
• It can contain only _ and white spaces
• First and last elements should be digits
• _ and white spaces should be in between 2 digits

Can I write a regular expression to validate the above things using php?

Example for valid entry: 231_901 347
Example for invalid entry: _123 567, 345__123

Also if possible, can you please write down the preg_match expression.

Here is the code which I tried:

$subject = "_012_345 69";
$pattern = '/[\d]{1}.[\d\s_]{5,10}.[\d]{1}$/';
$matches = preg_match($pattern, $subject);
echo($matches);

It should return 0 but it returns 1.

Answer 1

^(?=.{8,10}$)\d+(?:[ _]\d+)*$

Explanation:

^              # Start of string
 (?=.{8,10}$)  # Assert length 8-10
 \d+           # One or more digits
 (?:           # followed by
  [ _]         #  one space or underscore
  \d+          #  one or more digits
 )*            # zero or more times.           
$              # End of string