# How to validate GUID (Globally Unique Identifier) using Regular Expression

• Difficulty Level : Medium
• Last Updated : 19 Dec, 2022

Given string str, the task is to check whether the given string is a valid GUID (Globally Unique Identifier) or not by using Regular Expression.
The valid GUID (Globally Unique Identifier) must specify the following conditions:

1. It should be a 128-bit number.
2. It should be 36 characters (32 hexadecimal characters and 4 hyphens) long.
3. It should be displayed in five groups separated by hyphens (-).
4. Microsoft GUIDs are sometimes represented with surrounding braces.

Examples:

Input: str = “123e4567-e89b-12d3-a456-9AC7CBDCEE52”
Output: true
Explanation:
The given string satisfies all the above mentioned conditions. Therefore, it is a valid GUID (Globally Unique Identifier).
Input: str = “123e4567-h89b-12d3-a456-9AC7CBDCEE52”
Output: false
Explanation:
The given string contains ‘h’, the valid hexadecimal characters should be followed by character from a-f, A-F, and 0-9. Therefore, it is not a valid GUID (Globally Unique Identifier).
Input: str = “123e4567-h89b-12d3-a456”
Output: false
Explanation:
The given string has 20 characters. Therefore, it is not a valid GUID (Globally Unique Identifier).

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 GUID (Globally Unique Identifier) as mentioned below:

regex = “^[{]?[0-9a-fA-F]{8}-([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}[}]?\$”

• Where:
• ^ represents the starting of the string.
• [{]? represents the ‘{‘ character that is optional.
• [0-9a-fA-F]{8} represents the 8 characters from a-f, A-F, and 0-9.
• represents the hyphens.
• ([0-9a-fA-F]{4}-){3} represents the 4 characters from a-f, A-F, and 0-9 that is repeated 3 times separated by a hyphen (-).
• [0-9a-fA-F]{12} represents the 12 characters from a-f, A-F, and 0-9.
• [}]? represents the ‘}’ character that is optional.
• \$ 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``// GUID (Globally Unique Identifier) using Regular Expression``#include ``#include ``using` `namespace` `std;` `// Function to validate the GUID (Globally Unique Identifier).``bool` `isValidGUID(string str)``{` `  ``// Regex to check valid GUID (Globally Unique Identifier).``  ``const` `regex pattern(``"^[{]?[0-9a-fA-F]{8}-([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}[}]?\$"``);`  `  ``// If the GUID (Globally Unique Identifier)``  ``// is empty return false``  ``if` `(str.empty())``  ``{``     ``return` `false``;``  ``}` `  ``// Return true if the GUID (Globally Unique Identifier)``  ``// matched the ReGex``  ``if``(regex_match(str, pattern))``  ``{``    ``return` `true``;``  ``}``  ``else``  ``{``    ``return` `false``;``  ``}``}` `// Driver Code``int` `main()``{``  ``// Test Case 1:``  ``string str1 = ``"123e4567-e89b-12d3-a456-9AC7CBDCEE52"``;``  ``cout << isValidGUID(str1) << endl;` `  ``// Test Case 2:``  ``string str2 = ``"{123e4567-e89b-12d3-a456-9AC7CBDCEE52}"``;``  ``cout <<  isValidGUID(str2) << endl;` `  ``// Test Case 3:``  ``string str3 = ``"123e4567-h89b-12d3-a456-9AC7CBDCEE52"``;``  ``cout <<  isValidGUID(str3) << endl;` `  ``// Test Case 4:``  ``string str4 = ``"123e4567-h89b-12d3-a456"``;``  ``cout <<  isValidGUID(str4) << endl;` `  ``return` `0;``}` `// This code is contributed by yuvraj_chandra`

## Java

 `// Java program to validate``// GUID (Globally Unique Identifier)``// using regular expression` `import` `java.util.regex.*;` `class` `GFG {` `    ``// Function to validate``    ``// GUID (Globally Unique Identifier)``    ``// using regular expression``    ``public` `static` `boolean``    ``isValidGUID(String str)``    ``{``        ``// Regex to check valid``        ``// GUID (Globally Unique Identifier)``        ``String regex``            ``= ``"^[{]?[0-9a-fA-F]{8}"``              ``+ ``"-([0-9a-fA-F]{4}-)"``              ``+ ``"{3}[0-9a-fA-F]{12}[}]?\$"``;` `        ``// 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 str2``            ``= ``"123e4567-e89b-12d3"``              ``+ ``"-a456-9AC7CBDCEE52"``;``        ``System.out.println(``            ``isValidGUID(str2));` `        ``// Test Case 2:``        ``String str3``            ``= ``"{123e4567-e89b-12d3-"``              ``+ ``"a456-9AC7CBDCEE52}"``;``        ``System.out.println(``            ``isValidGUID(str3));` `        ``// Test Case 3:``        ``String str1``            ``= ``"123e4567-h89b-12d3-a456"``              ``+ ``"-9AC7CBDCEE52"``;``        ``System.out.println(``            ``isValidGUID(str1));` `        ``// Test Case 4:``        ``String str4``            ``= ``"123e4567-h89b-12d3-a456"``;``        ``System.out.println(``            ``isValidGUID(str4));``    ``}``}`

## Python3

 `# Python3 program to validate``# GUID (Globally Unique Identifier)``# using regular expression``import` `re` `# Function to validate GUID``# (Globally Unique Identifier)``def` `isValidGUID(``str``):` `    ``# Regex to check valid``    ``# GUID (Globally Unique Identifier)``    ``regex ``=` `"^[{]?[0-9a-fA-F]{8}"` `+` `"-([0-9a-fA-F]{4}-)"` `+` `"{3}[0-9a-fA-F]{12}[}]?\$"``        ` `    ``# 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 ``=` `"123e4567-e89b-12d3"` `+` `"-a456-9AC7CBDCEE52"``print``(isValidGUID(str1))` `# Test Case 2:``str2 ``=` `"{123e4567-e89b-12d3-"` `+` `"a456-9AC7CBDCEE52}"``print``(isValidGUID(str2))` `# Test Case 3:``str3 ``=` `"123e4567-h89b-12d3-a456"` `+` `"-9AC7CBDCEE52"``print``(isValidGUID(str3))` `# Test Case 4:``str4 ``=` `"123e4567-h89b-12d3-a456"``print``(isValidGUID(str4))` `# This code is contributed by avanitrachhadiya2155`

## C#

 `// C# program to validate``// GUID (Globally Unique Identifier) using Regular Expression``using` `System;``using` `System.Text.RegularExpressions;``class` `GFG``{` `  ``// Main Method``  ``static` `void` `Main(``string``[] args)``  ``{` `    ``// Input strings to Match``    ``//GUID (Globally Unique Identifier)` `    ``string``[] str={``"123e4567-e89b-12d3-a456-9AC7CBDCEE52"``,``"{123e4567-e89b-12d3-a456-9AC7CBDCEE52}"``,``"123e456-h89b-12d3-a456-9AC7CBDCEE52"``,``"123e4567-h89b-12d3-a456"``};``    ``foreach``(``string` `s ``in` `str) {``      ``Console.WriteLine( isValidGUID(s) ? ``"true"` `: ``"false"``);``    ``}``    ``Console.ReadKey(); }` `  ``// method containing the regex``  ``public` `static` `bool` `isValidGUID(``string` `str)``  ``{``    ``string` `strRegex = ``@"^[{]?[0-9a-fA-F]{8}-([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}[}]?\$"``;``    ``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``// GUID (Globally Unique Identifier) using Regular Expression` `// Function to validate the``// GUID ``function` `isValidGUID(str) {``    ``// Regex to check valid``    ``// GUID ``    ``let regex = ``new` `RegExp(/^[{]?[0-9a-fA-F]{8}-([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}[}]?\$/);` `    ``// 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 =  ``"123e4567-e89b-12d3"``              ``+ ``"-a456-9AC7CBDCEE52"``;``console.log(isValidGUID(str1));` `// Test Case 2:``let str2 = ``"{123e4567-e89b-12d3-"``              ``+ ``"a456-9AC7CBDCEE52}"``;``console.log(isValidGUID(str2));` `// Test Case 3:``let str3 =  ``"123e4567-h89b-12d3-a456"``              ``+ ``"-9AC7CBDCEE52"``;``console.log(isValidGUID(str3));` `// Test Case 4:``let str4 = ``"123e4567-h89b-12d3-a456"``;``console.log(isValidGUID(str4));`  `// This code is contributed by Rahul Chauhan`

Output:

```true
true
false
false```

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

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