How to validate pin code of India using Regular Expression

Given a string of positive number ranging from 0 to 9, the task is to check whether the number is valid pin code or not by using a Regular Expression.

The valid pin code of India must satisfy the following conditions. 

1. It can be only six digits.
2. It should not start with zero.
3. First digit of the pin code must be from 1 to 9.
4. Next five digits of the pin code may range from 0 to 9.
5. It should allow only one white space, but after three digits, although this is optional.

Examples:  

Input: num = "132103" 
Output: true 
Explanation: 
The given number satisfies all the above mentioned conditions.

Input: num = "201 305" 
Output: true 
Explanation: 
The given number satisfies all the above mentioned conditions.

Input: num = "014205" 
Output: false 
Explanation: 
The given number start with zero, therefore it is not a valid pin code of India.

Input: num = "1473598" 
Output: false 
Explanation: 
The given number contains seven digits, therefore it is not a valid pin code of India.  

Approach: This problem can be used by using Regular Expression.  

1. Get the number.

2. Create a regular expression to validate pin code of India as mentioned below: 

 
regex = "^[1-9]{1}[0-9]{2}\\s{0, 1}[0-9]{3}$";

Where: 

• ^ represents the starting of the number.
• [1-9]{1} represents the starting digit in the pin code ranging from 1 to 9.
• [0-9]{2} represents the next two digits in the pin code ranging from 0 to 9.
• \\s{0, 1} represents the white space in the pin code that can occur once or never.
• [0-9]{3} represents the last three digits in the pin code ranging from 0 to 9.
• $ represents the ending of the number.

3. Match the given number with the regex, in Java, this can be done by using Pattern.matcher().

4. Return true if the number matches with the given regex, else return false.

Below is the implementation of the above approach.  

// C++ program to validate the pin code
// of India using Regular Expression.
#include <bits/stdc++.h>
using namespace std;

// Function to validate the pin code of India.
bool isValidPinCode(string pinCode)
{
    
    // Regex to check valid pin code of India.
    const regex pattern("^[1-9]{1}[0-9]{2}\\s{0,1}[0-9]{3}$");

    // If the pin code is empty
    // return false
    if (pinCode.empty())
    {
        return false;
    }

    // Return true if the pin code
    // matched the ReGex
    if (regex_match(pinCode, pattern)) 
    {
        return true;
    }
    else 
    {
        return false;
    }
}

void print(bool n)
{
    if (n == 0) 
    {
        cout << "False" << endl;
    }
    else 
    {
        cout << "True" << endl;
    }
}

// Driver Code.
int main()
{
    
    // Test Case 1:
    string num1 = "132103";
    cout << num1 + ": ";
    print(isValidPinCode(num1));

    // Test Case 2:
    string num2 = "201 305";
    cout << num2 + ": ";
    print(isValidPinCode(num2));

    // Test Case 3:
    string num3 = "014205";
    cout << num3 + ": ";
    print(isValidPinCode(num3));

    // Test Case 4:
    string num4 = "1473598";
    cout << num4 + ": ";
    print(isValidPinCode(num4));

    return 0;
}

// This code is contributed by nirajgusain5

// Java program to validate the pin code
// of India using Regular Expression.

import java.util.regex.*;

class GFG {

    // Function to validate the pin code of India.
    public static boolean isValidPinCode(String pinCode)
    {

        // Regex to check valid pin code of India.
        String regex
            = "^[1-9]{1}[0-9]{2}\\s{0,1}[0-9]{3}$";

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

        // If the pin code is empty
        // return false
        if (pinCode == null) {
            return false;
        }

        // Pattern class contains matcher() method
        // to find matching between given pin code
        // and regular expression.
        Matcher m = p.matcher(pinCode);

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

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

        // Test Case 1:
        String num1 = "132103";
        System.out.println(
            num1 + ": "
            + isValidPinCode(num1));

        // Test Case 2:
        String num2 = "201 305";
        System.out.println(
            num2 + ": "
            + isValidPinCode(num2));

        // Test Case 3:
        String num3 = "014205";
        System.out.println(
            num3 + ": "
            + isValidPinCode(num3));

        // Test Case 4:
        String num4 = "1473598";
        System.out.println(
            num4 + ": "
            + isValidPinCode(num4));
    }
}

# Python3 program to validate the  
# pin code of India using Regular 
# Expression. 
import re

# Function to validate the pin code
# of India. 
def isValidPinCode(pinCode):
    
    # Regex to check valid pin code
    # of India.
    regex = "^[1-9]{1}[0-9]{2}\\s{0,1}[0-9]{3}$"; 

    # Compile the ReGex 
    p = re.compile(regex);
    
    # If the pin code is empty
    # return false
    if (pinCode == ''):
        return False;
        
    # Pattern class contains matcher() method
    # to find matching between given pin code
    # and regular expression.
    m = re.match(p, pinCode);
    
    # Return True if the pin code
    # matched the ReGex else False
    if m is None:
        return False
    else:
        return True

# Driver code 
if __name__ == "__main__":
    
    # Test case 1
    num1 = "132103";
    print(num1, ": ", isValidPinCode(num1));
    
    # Test case 2:
    num2 = "201 305";
    print(num2, ": ", isValidPinCode(num2));
    
    # Test case 3:
    num3 = "014205";
    print(num3, ": ", isValidPinCode(num3));
    
    # Test case 4:
    num4 = "1473598";
    print(num4, ": ", isValidPinCode(num4));
    
# This code is contributed by AnkitRai01

// C# program to validate the
//the pin code of India 
//using Regular Expressions
using System;
using System.Text.RegularExpressions;
class GFG
{

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

    // Input strings to Match
    //the pin code of India 
    string[] str={"132103","201 305","014205","1473598"};
    foreach(string s in str) {
      Console.WriteLine( isValidPinCode(s) ? "true" : "false");
    }
    Console.ReadKey(); }

  // method containing the regex
  public static bool isValidPinCode(string str)
  {
    string strRegex = @"^[1-9]{1}[0-9]{2}\s{0,1}[0-9]{3}$";
    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
// Pincode of India using Regular Expression

// Function to validate the
// Pincode of India
function isValidPinCode(str) {
    // Regex to check valid
    // Pincode of India
    let regex = new RegExp(/^[1-9]{1}[0-9]{2}\s{0,1}[0-9]{3}$/);

    // 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 = "132103";
console.log(isValidPinCode(str1));

// Test Case 2:
let str2 = "201 305";
console.log(isValidPinCode(str2));

// Test Case 3:
let str3 = "014205";
console.log(isValidPinCode(str3));

// Test Case 4:
let str4 = "1473598";
console.log(isValidPinCode(str4));

132103: true
201 305: true
014205: false
1473598: false

Time Complexity : O(1)

Space Complexity : O(1)