How to validate Indian Passport number using Regular Expression

Given a string str of alphanumeric characters, the task is to check whether the given string is a valid passport number or not by using Regular Expression. 

A valid passport number in India must satisfy the following conditions: 

1. It should be eight characters long.
2. The first character should be an uppercase alphabet.
3. The next two characters should be a number, but the first character should be any number from 1-9 and the second character should be any number from 0-9.
4. It should be zero or one white space character.
5. The next four characters should be any number from 0-9.
6. The last character should be any number from 1-9.

Illustration:

Input: str = "A2096457"; 
Output: true 
Explanation: The given string satisfies all the above mentioned conditions. Therefore it is a valid passport number of India. 

Input: str = "12096457"; 
Output: false 
Explanation: The given string doesn't starts with an upper case alphabet. Therefore it is not a valid passport number of India. 

Input: str = "A209645704"; 
Output: false 
Explanation: The given string contains 10 characters. Therefore it is not a valid passport number of India. 

Approach: The idea is to use Regular Expression to solve this problem. The following steps can be followed to compute the answer. 

1. Get the String.
2. Create a regular expression to check valid passport number of India as mentioned below: 

regex = "^[A-PR-WY][1-9]\\d\\s?\\d{4}[1-9]$"; 

Where: 

^ represents the starting of the string.
[A-PR-WY] represents the string that should start with A-Z excluding Q, X, and Z.
[1-9] represents the second character should be any number from 1-9.
\\d represents the third character should be any number from 0-9.
\\s? represents the string should be zero or one white space character.
\\d{4} represents the next four characters should be any number from 0-9.
[1-9] represents the last character should be any number from 1-9.
$ represents the ending of the string.

1. Match the given string with the Regular Expression. In Java, this can be done by using Pattern.matcher().
2. Return true if the string matches with the given regular expression, else return false.

Below is the implementation of the above approach:

C++

// C++ program to validate the
// passport number
// using Regular Expression
#include <iostream>
#include <regex>
using namespace std;

// Function to validate the passport number
bool isValidPassportNo(string str)
{
    // Regex to check valid passport number
    const regex pattern("^[A-PR-WY][1-9]"
                        "\\d\\s?\\d{4}[1-9]$");

    // If the passport number
    // is empty return false
    if (str.empty()) {
        return false;
    }

    // Return true if the passport number
    // matched the ReGex
    if (regex_match(str, pattern)) {
        return true;
    }
    else {
        return false;
    }
}

// Driver Code
int main()
{
    // Test Case 1:
    string str1 = "A21 90457";
    cout << isValidPassportNo(str1) << endl;

    // Test Case 2:
    string str2 = "A0296457";
    cout << isValidPassportNo(str2) << endl;

    // Test Case 3:
    string str3 = "Q2096453";
    cout << isValidPassportNo(str3) << endl;

    // Test Case 4:
    string str4 = "12096457";
    cout << isValidPassportNo(str4) << endl;

    // Test Case 5:
    string str5 = "A209645704";
    cout << isValidPassportNo(str5) << endl;

    return 0;
}

// This code is contributed by yuvraj_chandra

Java

// Java program to validate
// passport number of India
// using regular expression

import java.util.regex.*;

class GFG {

    // Function to validate
    // passport number of India
    // using regular expression
    public static boolean isValidPassportNo(String str)
    {
        // Regex to check valid.
        // passport number of India
        String regex = "^[A-PR-WY][1-9]\\d"
                       + "\\s?\\d{4}[1-9]$";

        // Compile the ReGex
        Pattern p = Pattern.compile(regex);

        // If the string is empty
        // return false
        if (str == null) {
            return false;
        }

        // Find match between given string
        // and regular expression
        // using Pattern.matcher()
        Matcher m = p.matcher(str);

        // Return if the string
        // matched the ReGex
        return m.matches();
    }

    // Driver code
    public static void main(String args[])
    {

        // Test Case 1:
        String str1 = "A21 90457";
        System.out.println(isValidPassportNo(str1));

        // Test Case 2:
        String str2 = "A0296457";
        System.out.println(isValidPassportNo(str2));

        // Test Case 3:
        String str3 = "Q2096453";
        System.out.println(isValidPassportNo(str3));

        // Test Case 4:
        String str4 = "12096457";
        System.out.println(isValidPassportNo(str4));

        // Test Case 5:
        String str5 = "A209645704";
        System.out.println(isValidPassportNo(str5));
    }
}

Python3

# Python3 program to validate passport
# number of India using regular expression
import re

# Function to validate the pin code
# of India.


def isValidPassportNo(string):

    # Regex to check valid pin code
    # of India.
    regex = "^[A-PR-WY][1-9]\\d" +\
            "\\s?\\d{4}[1-9]$"

    # Compile the ReGex
    p = re.compile(regex)

    # If the string is empty
    # return false
    if (string == ''):
        return False

    # Pattern class contains matcher()
    # method to find matching between
    # given string and regular expression.
    m = re.match(p, string)

    # Return True if the string
    # matched the ReGex else False
    if m is None:
        return False
    else:
        return True


# Driver code.
if __name__ == "__main__":

    # Test Case 1
    str1 = "A21 90457"
    print(isValidPassportNo(str1))

    # Test Case 2:
    str2 = "A0296457"
    print(isValidPassportNo(str2))

    # Test Case 3:
    str3 = "Q2096453"
    print(isValidPassportNo(str3))

    # Test Case 4:
    str4 = "12096457"
    print(isValidPassportNo(str4))

    # Test Case 5:
    str5 = "A209645704"
    print(isValidPassportNo(str5))

# This code is contributed by AnkitRai01

C#

// C# program to validate
// passport number of India
// using regular expression
using System;
using System.Text.RegularExpressions;
class GFG
{

  // Main Method
  static void Main(string[] args)
  {

    // Input strings to Match
    // Valid Passport
    string[] str={"A21 90457","A0296457","Q2096453","12096457",
                  "A209645704"};
    foreach(string s in str) {
      Console.WriteLine( isValidPassportNo(s) ? "true" : "false");
    }
    Console.ReadKey(); }

  // method containing the regex
  public static bool isValidPassportNo(string str)
  {
    string strRegex = @"^[A-PR-WY][1-9]\d\s?\d{4}[1-9]$";
    Regex re = new Regex(strRegex);
    if (re.IsMatch(str))
      return (true);
    else
      return (false);
  }
}

// This code is contributed by Rahul Chauhan

Javascript

// Javascript program to
// validate passport
// number of India using regular expression

// Function to validate the
// Passport Number
function isValidPassportNo(str) {
    // Regex to check valid
    // Passport Number
    let regex = new RegExp(/^[A-PR-WY][1-9]\d\s?\d{4}[1-9]$/);

    // if str
    // is empty return false
    if (str == null) {
        return "false";
    }

    // Return true if the str
    // matched the ReGex
    if (regex.test(str) == true) {
        return "true";
    }
    else {
        return "false";
    }
}

// Driver Code
// Test Case 1:
let str1 = "A21 90457";
console.log(isValidPassportNo(str1));

// Test Case 2:
let str2 = "A0296457";
console.log(isValidPassportNo(str2));

// Test Case 3:
let str3 = "Q2096453";
console.log(isValidPassportNo(str3));

// Test Case 4:
let str4 = "12096457";
console.log(isValidPassportNo(str4));

// Test Case 5:
let str5 = "A209645704";
console.log(isValidPassportNo(str5));


// This code is contributed by Rahul Chauhan

Output

true
false
false
false
false

Time Complexity: O(N) for each test case, where N is the length of the given string.
Auxiliary Space: O(1)