Program to check valid mobile number

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++
Java
Python
// C++ program to check if given mobile number// is valid.#include <iostream>#include <regex>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 Codeint main(){  string s = "347873923408";  if(isValid(s))  {      cout << "Valid";  }  else  {      cout<<"Invalid";  }  return 0;}  // This code is contributed by yuvraj_chandra
// 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 codepublic static void main(String[] args){    String s = "347873923408";          if (isValid(s))         System.out.println("Valid Number");         else        System.out.println("Invalid Number");     }}
# Python program to check if # given mobile number is validimport 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 Codes = "347873923408"if (isValid(s)):     print ("Valid Number")     else :    print ("Invalid Number")     # This code is contributed by rishabh_jain 
Output:
Invalid Number
aimformohan
yuvraj_chandra
dhaneshkanak
java-regular-expression
Java-String-Programs
Java-Strings
Java
Java-Strings
Java
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