Hi team

I want to group a bunch of constants in a class in C++, how to I do that?

// in ver.h
class VER{
    public:
        static const MAJOR = 0;
        static const MINOR = 1;
};

// in main.cpp
#include <iostream>
#include "ver.h"

int main(int argc, char *argv[]){
    printf("ver: %u.%u\n", VER.MAJOR, VER.MINOR);
    return 0;
}

 

Pick your poison, there's a dozen ways to do it. Make them const, use #define, put them in a struct, an enum, their own class, just name them with similar names, etc.. If the goal is to store version information, you probably want that pretty front and center on a top level file, not buried down in the project somewhere. #define is commonly used, but again there are multiple ways to do it, all with their own pros and cons.

 

Pick your poison, there's a dozen ways to do it. Make them const, use #define, put them in a struct, an enum, their own class, just name them with similar names, etc.. If the goal is to store version information, you probably want that pretty front and center on a top level file, not buried down in the project somewhere. #define is commonly used, but again there are multiple ways to do it, all with their own pros and cons.

I normally use #define or struct in C, but just wondering if there is a better way to do it in C++.

 

IIRC, you can declare static objects outside the class, which are then accessible to all instances of the class.

I just pulled up a project from ca. 1995, and here is the pertinent line:

int cRoot::m_countobj=0;   //Static. Holds last handle used.

This line is located in the cRoot class source file, prior to the definition of the cRoot class.

I assume one could add const prior to the int to make it constant.

 

Hi team

I want to group a bunch of constants in a class in C++, how to I do that?

// in ver.h
class VER{
    public:
        static const MAJOR = 0;
        static const MINOR = 1;
};

// in main.cpp
#include <iostream>
#include "ver.h"

int main(int argc, char *argv[]){
    printf("ver: %u.%u\n", VER.MAJOR, VER.MINOR);
    return 0;
}

If you create the item within a class wouldn't the memory be allocated on the creation of the object? I'm not sure of the purpose of the MAJOR or MINOR constants but perhaps these should be #define MAJOR 0 & #define MINOR 1 in this case

 

I prefer enums like in the following. Note I could typedef the enum but I tend not to bother.

class CMyClass {
	private:
		//
		enum {HEADER_LEN=4};
		enum {HEADER_VERSION=0};
		enum {HEADER_TARGET=1};
		enum {HEADER_BYTES=2};
		enum {HEADER_CRC=3};
		//...
	public:
		DWORD Read();
		// Read() returns one of.
		enum {
			ERROR, NODATA, SUCCESS
		};
		//...
};