How to validate SSN (Social Security Number) using Regular Expression

Given string str, the task is to check whether the given string is valid SSN (Social Security Number) or not by using Regular Expression. 
The valid SSN (Social Security Number) must satisfy the following conditions: 

1. It should have 9 digits.
2. It should be divided into 3 parts by hyphen (-).
3. The first part should have 3 digits and should not be 000, 666, or between 900 and 999.
4. The second part should have 2 digits and it should be from 01 to 99.
5. The third part should have 4 digits and it should be from 0001 to 9999.

Examples:

Input: str = “856-45-6789”; 
Output: true 
Explanation: The given string satisfies all the above mentioned conditions. Therefore, it is a valid SSN (Social Security Number).

Input: str = “000-45-6789”; 
Output: false 
Explanation: The given string starts with 000. Therefore, it is not a valid SSN (Social Security Number).

Input: str = “856-452-6789”; 
Output: false 
Explanation: The second part of this string has 3 digits. Therefore, it is not a valid SSN (Social Security Number).

Input: str = “856-45-0000”; 
Output: false 
Explanation: The third part of this string is 0000. Therefore, it is not a valid SSN (Social Security Number). 

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

• Get the String.
• Create a regular expression to check valid SSN (Social Security Number) as mentioned below:

regex = "^(?!666|000|9\\d{2})\\d{3}-(?!00)\\d{2}-(?!0{4})\\d{4}$";

• Where: 
  • ^ represents the starting of the string.
  • (?!666|000|9\\d{2})\\d{3} represents the first 3 digits should not start with 000, 666, or between 900 and 999.
  • – represents the string followed by a hyphen (-).
  • (?!00)\\d{2} represents the next 2 digits should not start with 00 and it should be any from 01-99.
  • – represents the string followed by a hyphen (-).
  • (?!0{4})\\d{4} represents the next 4 digits can’t 0000 and it should be any from 0001-9999.
  • $ represents the ending of the string.
• Match the given string with the regular expression. In Java, this can be done by using Pattern.matcher().
• 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
// SSN (Social Security Number)
// using Regular Expression
#include <iostream>
#include <regex>
using namespace std;

// Function to validate the SSN
// (Social Security Number)
bool isValidSSN(string str)
{

    // Regex to check valid SSN
    // (Social Security Number)
    const regex pattern("^(?!666|000|9\\d{2})"
                        "\\d{3}-(?!00)"
                        "\\d{2}-(?!0{4})\\d{4}$");

    // If the SSN (Social Security Number)
    // is empty return false
    if (str.empty())
    {
        return false;
    }

    // Return true if the SSN
    // (Social Security Number)
    // matched the ReGex
    if (regex_match(str, pattern))
    {
        return true;
    }
    else {
        return false;
    }
}

// Driver Code
int main()
{
    // Test Case 1:
    string str1 = "856-45-6789";
    cout << isValidSSN(str1) << endl;

    // Test Case 2:
    string str2 = "000-45-6789";
    cout << isValidSSN(str2) << endl;

    // Test Case 3:
    string str3 = "856-452-6789";
    cout << isValidSSN(str3) << endl;

    // Test Case 4:
    string str4 = "856-45-0000";
    cout << isValidSSN(str4) << endl;

    return 0;
}

// This code is contributed by yuvraj_chandra

Java

// Java program to check valid
// SSN (Social Security Number) using
// regex.
import java.util.regex.*;
class GFG {

    // Function to validate
    // SSN (Social Security Number).
    public static boolean isValidSSN(String str)
    {
        // Regex to check SSN
        // (Social Security Number).
        String regex = "^(?!666|000|9\\d{2})\\d{3}"
                       + "-(?!00)\\d{2}-"
                       +"(?!0{4})\\d{4}$";

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

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

        // Pattern class contains matcher()
        //  method to find matching between
        //  given string and regular expression.
        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 = "856-45-6789";
        ;
        System.out.println(isValidSSN(str1));

        // Test Case 2:
        String str2 = "000-45-6789";
        ;
        System.out.println(isValidSSN(str2));

        // Test Case 3:
        String str3 = "856-452-6789";
        System.out.println(isValidSSN(str3));

        // Test Case 4:
        String str4 = "856-45-0000";
        System.out.println(isValidSSN(str4));
    }
}

Python3

# Python3 program to validate
# SSN (Social Security Number)
# using regular expression
import re

# Function to validate SSN
# (Social Security Number).


def isValidSSN(str):

    # Regex to check valid
    # SSN (Social Security Number).
    regex = "^(?!666|000|9\\d{2})\\d{3}-(?!00)\\d{2}-(?!0{4})\\d{4}$"

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

    # If the string is empty
    # return false
    if (str == None):
        return False

    # Return if the string
    # matched the ReGex
    if(re.search(p, str)):
        return True
    else:
        return False

# Driver code


# Test Case 1:
str1 = "856-45-6789"
print(isValidSSN(str1))

# Test Case 2:
str2 = "000-45-6789"
print(isValidSSN(str2))

# Test Case 3:
str3 = "856-452-6789"
print(isValidSSN(str3))

# Test Case 4:
str4 = "856-45-0000"
print(isValidSSN(str4))

# This code is contributed by avanitrachhadiya2155

C#

// C# program to validate the
// SSN (Social Security Number)
//using Regular Expressions
using System;
using System.Text.RegularExpressions;
class GFG
{

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

        // Input strings to Match
        // valid SSN (Social Security Number)
        string[] str={"856-45-6789","000-45-6789" ,"856-452-6789","856-45-0000"};
        foreach(string s in str) {
 Console.WriteLine( isValidSSN(s) ? "true" : "false");
 }
 Console.ReadKey(); }

    // method containing the regex
    public static bool isValidSSN(string str)
    {
        string strRegex = @"^(?!666|000|9\d{2})\d{3}-(?!00)\d{2}-(?!0{4})\d{4}$";
        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
// SSN (Social Security Number) using Regular Expression

// Function to validate the
// SSN Code
function isValidSSN(str) {
    // Regex to check valid
    // SSN CODE
    let regex = new RegExp(/^(?!666|000|9\d{2})\d{3}-(?!00)\d{2}-(?!0{4})\d{4}$/);

    //  if str CODE
    // 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 = "856-45-6789";
console.log(isValidSSN(str1));

// Test Case 2:
let str2 = "000-45-6789";
console.log(isValidSSN(str2));

// Test Case 3:
let str3 = "856-452-6789";
console.log(isValidSSN(str3));

// Test Case 4:
let str4 = "856-45-0000";
console.log(isValidSSN(str4));

// This code is contributed by Rahul Chauhan

Output

true
false
false
false

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