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# 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.
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++

 `// C++ program to validate the pin code``// of India using Regular Expression.``#include ``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

 `// 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

 `# 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#

 `// 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``// 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));`

Output:

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

Time Complexity : O(1)

Space Complexity : O(1)