UUIDs in 10 Languages — Part 1: UUID Generation in C and C++

UUIDs aren’t just for high-level application frameworks. They’re also essential in the foundations of operating systems, databases, and distributed protocols — which often means C and C++.

But generating UUIDs in these languages isn’t as simple as calling uuid() in Python. You have to pick the right libraries, manage memory properly, and often handle formatting manually.

Here’s how to generate UUIDs properly in C and C++, with idiomatic examples and common pitfalls.

⚙️ C: Using `libuuid` (Linux/Unix)

Most Linux systems ship with libuuid, part of the util-linux package.

🔧 Installation

On Ubuntu/Debian:

bash

sudo apt install uuid-dev

📦 Basic UUIDv4 Example in C

#include <stdio.h>
#include <uuid/uuid.h>

int main() {
    uuid_t uuid;
    char uuid_str[37]; // 36 chars + null terminator

    uuid_generate_random(uuid);
    uuid_unparse_lower(uuid, uuid_str);

    printf("Generated UUID: %s
", uuid_str);
    return 0;
}

✅ Notes

uuid_generate() is a hybrid generator (might use MAC + time or randomness)
uuid_generate_random() forces version 4 (fully random)
uuid_unparse_lower() is preferred for lowercase formatting

🪟 Windows: `UuidCreate` and `UuidToString`

📦 Example in Windows (C)

#include <rpc.h>
#include <stdio.h>

#pragma comment(lib, "Rpcrt4.lib")

int main() {
    UUID uuid;
    UuidCreate(&uuid);

    RPC_CSTR str;
    UuidToStringA(&uuid, &str);

    printf("UUID: %s
", str);

    RpcStringFreeA(&str);
    return 0;
}

⚠️ Caveats

Windows APIs generate UUIDv1-style (time + MAC)
Requires linking against Rpcrt4.lib
Strings are allocated — remember to free them!

💡 C++: Use Boost.UUID for Cleaner Code

The Boost library provides a powerful and portable UUID implementation.

🔧 Installation (Ubuntu)

bash

sudo apt install libboost-all-dev

📦 Example (UUIDv4 in C++)

cpp

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

int main() {
    boost::uuids::random_generator gen;
    boost::uuids::uuid id = gen();

    std::cout << "UUID: " << id << std::endl;
    return 0;
}

📦 Alternative: Name-based UUID

cpp

#include <boost/uuid/name_generator.hpp>

boost::uuids::name_generator gen_ns(boost::uuids::ns::dns());
auto id = gen_ns("example.com");

🧪 Testing and Validating UUIDs

Whether you're generating or parsing UUIDs:

Validate against a regex: [0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}
Use Boost’s comparison operators (==, <, etc.)
In C, verify uuid_compare() if checking equality

🧠 Best Practices

Concern	Recommendation
Format safety	Use `uuid_unparse_lower()` in C
Version control	Prefer `uuid_generate_random()` for UUIDv4
Platform portability	Prefer Boost in C++
Thread safety	Most UUID APIs are thread-safe, but check docs
Memory management	Always free RPC strings on Windows

🧰 Where You'll See This in the Real World

Filesystem labels (ext4 uses UUIDs)
Systemd machine IDs
Kubernetes node IDs (container runtimes)
Embedded platforms and serial number IDs
Inter-process correlation (Windows RPC, UNIX daemons)

Final Thoughts

UUIDs in C and C++ may take more setup — but they’re a powerful tool when used correctly.

Whether you’re building a high-performance game engine, a system daemon, or a distributed storage node, these identifiers provide traceability, correlation, and uniqueness — all with the performance and precision these languages demand.

🧱 Part 2 up next: Rust, Go, and C# — with even more expressive UUID options.

"UUIDs in 10 Languages" Part 1: UUID Generation in C and C++