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

Given a 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).

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: The idea is to use the 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 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 starts 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 starts 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.
3. Match the given string with the regular expression. In Java, this can be done by using Pattern.matcher().
4. Return true if the string matches with the given regular expression, else return false.

Below is the implementation of the above approach:

## 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)); ` `    ``} ` `} `

Output:

```true
false
false
false
```

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