I'm trying to understand how the hpp, cpp, and main all work together. for this example I'm working on a code that coverts ARGB to RGBA and I'm confused on what to put in each file.

This is my code:

color.hpp

using namespace std;
#include <stdio.h>
#include <stdio.h>
#include <iostream>
#ifndef colors_hpp
#define colors_hpp
 /* colors_hpp */

string getHex();
uint32_t fromArgb();
#endif

color.cpp

#include "colors.hpp"
#include <iostream>
#include <stdio.h>
#include <stdarg.h>
#include <stdint.h>

template <typename T>
struct Color
{
        public:
        /* Works fine!!! */
        Color(uint8_t r, uint8_t g, uint8_t b, uint8_t a = 255)
        {
            buffer((r << 0) | (g << 8) | (b << 16) | (a << 24));
        }

        Color(const uint32_t argb)
        {
          buffer = fromArgb(argb);
        }


        inline uint32_t fromArgb(uint32_t argb)
        {
            return
                // Source is in format: 0xAARRGGBB
                ((argb & 0x00FF0000) >> 16)  | //____RR
                ((argb & 0x0000FF00))        | //_GG_
                ((argb & 0x000000FF) << 16)  | //__BB_
                ((argb & 0xFF000000));         //AA____
                // Return value is in format:  0xAABBGGRR
        }

        inline uint8_t getRed(void) const
        {
            return (buffer >> 0) & 0xFF;
        }

        inline uint8_t getGreen(void) const
        {
            return (buffer >> 8) & 0xFF;
        }

        inline uint8_t getBlue(void) const
        {
            return (buffer >> 16) & 0xFF;
        }

        inline uint8_t getAlpha(void) const
        {
            return (buffer >> 24) & 0xFF;
        }

        /* Works fine!!!*/
        std::string getHex(void) const
        {
            std::string result    = "#";
            char colorBuffer[255] = {}; 

            // Order is intentionally end to beginning
            sprintf_s(colorBuffer, 255, "%.2X", getAlpha());
            result.append(colorBuffer);

            sprintf_s(colorBuffer, 255, "%.2X", getBlue());
            result.append(colorBuffer);

            sprintf_s(colorBuffer, 255, "%.2X", getGreen());
            result.append(colorBuffer);

            sprintf_s(colorBuffer, 255, "%.2X", getRed());
            result.append(colorBuffer);

            return result;
        }

        private:
         uint32_t buffer;
};

main.cpp

int main(int argc, char**argv) {
    fromArgb(255,255,0,0);
    getHex();
    
}

I'm not able to understand where to use or call the struct or functions, and i'm really confused on what to put in hpp, cpp, and main files.

CodePudding user response：

Some advice

1. Remove this template <typename T>

2. Move struct Color { ... }; to color.hpp (all of it, you can delete color.cpp, it is not needed).

3. Remove using namespace std; from color.hpp

4. Remove string getHex(); uint32_t fromArgb(); from color.hpp

5. change main to this

   int main(int argc, char**argv) {
       Color c;
       c.fromArgb(255,255,0,0);
       std::cout << c.getHex() << std::endl;
   }
   

The main problem seems to be that you don't know how objects work. In order to use the fromArgb and getHex methods you need a Color object. So in my code I declared a Color object like this Color c; and then I used that colour object like this c.fromArgb(255,255,0,0); and this c.getHex(). How to use classes and objects is a more important topic than how to organise your code into headers and cpp files.

I haven't tested these changes. If there are any further problems you can't figure out then ask again.