Program to check valid mobile number

• Difficulty Level : Easy
• Last Updated : 05 Oct, 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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