How to Automatically Convert C Enums to Strings Without Modifying Source Code?

How to Convert C Enums to Strings

When working with named C enums, you may encounter scenarios where converting an enum value to its corresponding string representation is necessary. While several approaches exist for this conversion, this article addresses a specific query regarding generating functions for converting all enums in a project to strings without modifying the source code.

X-Macros: A Comprehensive Solution

The recommended approach involves utilizing X-macros. An example implementation is presented below:

#include <iostream>

enum Colours {
#   define X(a) a,
#   include "colours.def"
#   undef X
    ColoursCount
};

char const* const colours_str[] = {
#   define X(a) #a,
#   include "colours.def"
#   undef X
    0
};

std::ostream&amp; operator<<(std::ostream&amp; os, enum Colours c)
{
    if (c >= ColoursCount || c < 0) return os << "???";
    return os << colours_str[c];
}

int main()
{
    std::cout << Red << Blue << Green << Cyan << Yellow << Magenta << std::endl;
}

In the colours.def file, define the enums as follows:

X(Red)
X(Green)
X(Blue)
X(Cyan)
X(Yellow)
X(Magenta)

This method provides a flexible way to generate conversion functions for all enums in your project without making any modifications to your source code.

Customizable String Generation

Alternatively, you can opt for a method that allows for customization of the generated string representations. The following code snippet illustrates how to achieve this:

#define X(a, b) a,
#define X(a, b) b,

X(Red, "red")
X(Green, "green")
// etc.

This approach provides greater control over the generated strings and can be particularly useful when you need specific customizations for your application.

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