Python Regex For Mobile Phone Number Validity Check

Because there was a huge response from readers towards the email validity check and Roman numerals validity check algorithms I wrote using python regex, I decided to write another common place validity check – mobile phone numbers validity check. Checking mobile phone numbers for validity promises to be easier than other validity checks.

 

To understand the code I will be using, I recommend you read the following earlier blog posts that discusses python regex syntax and methods: “How to find a match when you are dating floats" which is an introduction to python regex coached in story form, and “The Big Advantage of Understanding Python Regex Methods” which discusses three methods you will always use when looking for matches in python regex. At least, you will use one of the three.

Now that we have the fundamentals out of the way, let’s start coding.

Now the rule I will be using for valid mobile numbers are that: A valid mobile number is a ten digit number starting with a 7, 8, or 9. Simply that. I know you can do it on your own after reading the two earlier posts above. I know you can.

But would you like to see my implementation? Here it is below with explanations. The embedded python interpreter would ask you to input a mobile number that would be used for validation.

The really interesting part I think I should explain is the pattern. Other parts of the code should be clear to you but if they are not clear, check the links above. Now for the pattern (see line 3) I first stated that it starts with either a 7, 8, or 9 using a set notation for python regex, ^[789]. Then after the starting digits, there should be 9 digits after that and only 9 digits after, nothing more nothing less. This notation nails it: \d{d}$ with the $ signifying that the last digit is the end of the pattern. That’s that.

Note: In mobile numbers there are other rules like adding a + before the number or an 0. For the sake of simplicity in this post and helping you to get a hold on the fundamentals, I restricted my pattern to only the rule that it is a ten digit number starting with 7, 8, or 9. If you want to validate for additional rules, then experiment with python regex and send me your code about what you did. I would be happy to take a look at it. Remember, programming is all about being creative in problem solving.

Happy pythoning.