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Program to check valid mobile number
• Difficulty Level : Easy
• Last Updated : 03 Jun, 2021

Mobile Number validation criteria:

• The first digit should contain number between 7 to 9.
• The rest 9 digit can contain any number between 0 to 9.
• The mobile number can have 11 digits also by including 0 at the starting.
• The mobile number can be of 12 digits also by including 91 at the starting

The number which satisfies the above criteria, is a valid mobile Number.
Examples:

```Input : Enter Mobile Number:
7873923408
Output :Valid Mobile Number

Input : Enter Mobile Number:
5678729234
Output :Invalid Mobile Number```

Prerequisites : Java Regular Expressions

## C++

 `// C++ program to check if given mobile number``// is valid.``#include ``#include ``using` `namespace` `std;` `bool` `isValid(string s)``{``    ``// The given argument to pattern()``    ``// is regular expression. With the help of``    ``// regular expression we can validate mobile``    ``// number.``    ``// 1) Begins with 0 or 91``    ``// 2) Then contains 7 or 8 or 9.``    ``// 3) Then contains 9 digits``  ``const` `regex pattern(``"(0|91)?[7-9][0-9]{9}"``);` `  ``// regex_match() is used to``  ``// to find match between given number``  ``// and regular expression``  ``if``(regex_match(s, pattern))``  ``{``    ``return` `true``;``  ``}``  ``else``  ``{``    ``return` `false``;``  ``}``}` `// Driver Code``int` `main()``{``  ``string s = ``"347873923408"``;``  ``if``(isValid(s))``  ``{``      ``cout << ``"Valid"``;``  ``}``  ``else``  ``{``      ``cout<<``"Invalid"``;``  ``}``  ``return` `0;``}` `// This code is contributed by yuvraj_chandra`

## Java

 `// Java program to check if given mobile number``// is valid.``import` `java.util.regex.*;``import` `java.util.Scanner;` `class` `GFG{``    ` `public` `static` `boolean` `isValid(String s)``{``    ` `    ``// The given argument to compile() method``    ``// is regular expression. With the help of``    ``// regular expression we can validate mobile``    ``// number.``    ``// 1) Begins with 0 or 91``    ``// 2) Then contains 7 or 8 or 9.``    ``// 3) Then contains 9 digits``    ``Pattern p = Pattern.compile(``"(0|91)?[7-9][0-9]{9}"``);` `    ``// Pattern class contains matcher() method``    ``// to find matching between given number``    ``// and regular expression``    ``Matcher m = p.matcher(s);``    ``return` `(m.find() && m.group().equals(s));``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``String s = ``"347873923408"``;``    ` `    ``if` `(isValid(s))``        ``System.out.println(``"Valid Number"``);    ``    ``else``        ``System.out.println(``"Invalid Number"``);    ``}``}`

## Python

 `# Python program to check if``# given mobile number is valid``import` `re` `def` `isValid(s):``    ` `    ``# 1) Begins with 0 or 91``    ``# 2) Then contains 7 or 8 or 9.``    ``# 3) Then contains 9 digits``    ``Pattern ``=` `re.``compile``(``"(0|91)?[7-9][0-9]{9}"``)``    ``return` `Pattern.match(s)` `# Driver Code``s ``=` `"347873923408"``if` `(isValid(s)):``    ``print` `(``"Valid Number"``)    ``else` `:``    ``print` `(``"Invalid Number"``)`  `# This code is contributed by rishabh_jain`

Output:

`Invalid Number`

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