There are three effective ways to generate UUIDs or GUIDs in C: 1. Use the Boost library, which provides multi-version support and is simple to interface; 2. Manually generate Version 4 UUIDs suitable for simple needs; 3. Use platform-specific APIs (such as Windows' CoCreateGuid), without third-party dependencies. Boost is suitable for most modern projects, manual implementation is suitable for lightweight scenarios, and platform API is suitable for enterprise environments.

If you need to generate a UUID or GUID in C , there's no built-in standard library support for it prior to C 20, and even then, it's limited. So, most developers either use external libraries or implement their own solutions based on known UUID versions.

Here's how you can do it effectively depending on your needs and environment.

Use a Library Like boost::uuids

Boost is one of the most common and reliable ways to generate UUIDs in C . It supports multiple UUID versions and provides clean APIs.

• Install Boost (if not already installed) via package managers like vcpkg or directly from source.
• Include <boost></boost> and <boost></boost> .
• Use the random generator like this:

 #include <boost/uuid/uuid.hpp>
#include <boost/uuid/uuid_generators.hpp>
#include <boost/uuid/uuid_io.hpp>
#include <iostream>

int main() {
    boost::uuids::uuid uuid = boost::uuids::random_generator()();
    std::cout << uuid << std::endl;
    return 0;
}

This gives you a Version 4 UUID by default. If you need other versions, Boost has support for things like name-based (Version 3 or 5) and time-based (Version 1) UUIDs as well.

Generate Manually for Simple Needs

If you don't want to pull in a big library like Boost, you can generate a basic Version 4 UUID manually.

A Version 4 UUID looks like this: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
Where:

• The third group starts with "4" (indicating version 4).
• The fourth group starts with "8", "9", "a", or "b".

You can create a random string following that pattern using something like:

 #include <random>
#include <string>
#include <iostream>

std::string generate_uuid_v4() {
    static std::random_device rd;
    static std::mt19937 gen(rd());
    static std::uniform_int_distribution<> dis(0, 15);
    static std::uniform_int_distribution<> dis2(8, 11);

    std::string uuid = "xxxxxxx-xxxx-4xxx-yxxxx-xxxxxxxxxxxxxxxxx";
    for (int i = 0; i < uuid.size(); i) {
        if (uuid[i] == &#39;x&#39;) {
            int r = dis(gen);
            uuid[i] = "0123456789abcdef"[r];
        } else if (uuid[i] == &#39;y&#39;) {
            int r = dis2(gen);
            uuid[i] = "89ab"[r - 8];
        }
    }
    return uuid;
}

int main() {
    std::cout << generate_uuid_v4() << std::endl;
    return 0;
}

This isn't cryptographically secure but works fine for simple applications.

Use Platform-Specific APIs (Windows Example)

On Windows, you can use the native API CoCreateGuid , which is part of the COM library.

Steps:

• Include <objbase.h>
• Link against ole32.lib
• Call CoCreateGuid() to fill a GUID struct

Example:

 #include <objbase.h>
#include <iostream>

std::string guid_to_string(const GUID &guid) {
    char guidStr[37];
    sprintf_s(guidStr,
        "X- X- X- X- X X- XXXXXX",
        guid.Data1, guid.Data2, guid.Data3,
        guid.Data4[0], guid.Data4[1],
        guid.Data4[2], guid.Data4[3],
        guid.Data4[4], guid.Data4[5],
        guid.Data4[6], guid.Data4[7]);
    return std::string(guidStr);
}

int main() {
    CoInitialize(nullptr);
    GUID guid;
    CoCreateGuid(&guid);
    std::cout << guid_to_string(guid) << std::endl;
    CoUninitialize();
    return 0;
}

This method avoids third-party dependencies and uses OS-level tools, which can be helpful in enterprise environments.

Summary of Options

• Boost : Full-featured, easy to use, supports multiple UUID versions.
• Manual generation : Lightweight, good for basic needs, not secure.
• Platform-specific APIs : No external dependencies, but not portable.

Depending on your project setup and requirements, pick the method that fits best. For most modern projects, Boost is the easiest and safest bet unless you have strict dependency limits.

Basically that's it.

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