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Generate Random Colors in C++ - Hex, RGB & Qt QColor

Complete code tutorial with examples and best practices

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[ Code Example - Quick Summary ]

Language: C++

What: Generate random colors in C++ using hex strings, RGB values, and Qt QColor objects with modern C++11 random number generation.

Try it: Use our interactive Colors generator or integrate this code into your C++ application.

Generate random colors in C++ using hex strings, RGB values, and Qt QColor objects with modern C++11 random number generation. Looking for other languages? Check our code examples in PHP , JavaScript , Python , Java , C# , Ruby and Go or use our interactive web generator.

C++ Code Example

#include <iostream>
#include <random>
#include <sstream>
#include <iomanip>
#include <string>

class RandomColorGenerator {
private:
    std::random_device rd;
    std::mt19937 gen;
    std::uniform_int_distribution<> rgb_dist;
    std::uniform_int_distribution<> hue_dist;
    std::uniform_int_distribution<> percent_dist;

public:
    RandomColorGenerator()
        : gen(rd()),
          rgb_dist(0, 255),
          hue_dist(0, 360),
          percent_dist(0, 100) {}

    std::string randomHexColor() {
        std::stringstream ss;
        ss << "#"
           << std::hex << std::setfill('0')
           << std::setw(2) << rgb_dist(gen)
           << std::setw(2) << rgb_dist(gen)
           << std::setw(2) << rgb_dist(gen);
        return ss.str();
    }

    std::string randomRgbColor() {
        int r = rgb_dist(gen);
        int g = rgb_dist(gen);
        int b = rgb_dist(gen);
        return "rgb(" + std::to_string(r) + ", " +
               std::to_string(g) + ", " +
               std::to_string(b) + ")";
    }

    std::string randomHslColor() {
        int h = hue_dist(gen);
        int s = percent_dist(gen);
        int l = percent_dist(gen);
        return "hsl(" + std::to_string(h) + ", " +
               std::to_string(s) + "%, " +
               std::to_string(l) + "%)";
    }

    std::string randomPastelColor() {
        int h = hue_dist(gen);
        std::uniform_int_distribution<> pastel_s(25, 100);
        std::uniform_int_distribution<> pastel_l(70, 90);
        int s = pastel_s(gen);
        int l = pastel_l(gen);
        return "hsl(" + std::to_string(h) + ", " +
               std::to_string(s) + "%, " +
               std::to_string(l) + "%)";
    }

    struct RGB {
        int r, g, b;
    };

    RGB randomRgbStruct() {
        return {rgb_dist(gen), rgb_dist(gen), rgb_dist(gen)};
    }
};

int main() {
    RandomColorGenerator colorGen;

    std::cout << "Hex Color: " << colorGen.randomHexColor() << std::endl;
    std::cout << "RGB Color: " << colorGen.randomRgbColor() << std::endl;
    std::cout << "HSL Color: " << colorGen.randomHslColor() << std::endl;
    std::cout << "Pastel: " << colorGen.randomPastelColor() << std::endl;

    auto rgb = colorGen.randomRgbStruct();
    std::cout << "RGB Struct: (" << rgb.r << ", "
              << rgb.g << ", " << rgb.b << ")" << std::endl;

    return 0;
}

[EXPLANATION]

Modern C++ (C++11+) uses std::random_device for seed generation and std::mt19937 (Mersenne Twister) for high-quality random numbers. std::uniform_int_distribution generates uniformly distributed integers. For hex colors, use std::stringstream with std::hex and std::setw(2) for 2-digit hex values. RGB uses three random integers (0-255). Create member distributions in the class for efficiency instead of recreating them. For Qt applications, you can create QColor objects with RGB values.

Expected Output

Hex Color: #6b4e9a
RGB Color: rgb(187, 98, 143)
HSL Color: hsl(234, 67%, 54%)
Pastel: hsl(89, 78%, 85%)
RGB Struct: (142, 207, 89)

Common Use Cases

Generate colors for Qt GUI applications
Create color palettes for game development
Assign colors to 3D rendering objects
Generate test data for graphics libraries
Create random materials for OpenGL/Vulkan

Important Notes

Use std::mt19937 for better quality than rand()
std::random_device provides non-deterministic random seeds
Create distributions once and reuse for performance
Qt uses QColor(r, g, b) for RGB colors
For hex strings, std::setfill('0') pads with zeros

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