How Can I Easily Convert C Enums to Strings, Handling Typedefs and Unnamed Enums?

Hassle-Free C Enum Conversion to Strings

Suppose you encounter named enums in your C code:

enum MyEnum {
      FOO,
      BAR = 0x50
};

And you seek a script to generate a header featuring a conversion function for each enum:

char* enum_to_string(MyEnum t);

With a straightforward implementation like this:

char* enum_to_string(MyEnum t){
      switch(t){
         case FOO:
            return "FOO";
         case BAR:
            return "BAR";
         default:
            return "INVALID ENUM";
      }
 }

However, things get tricky with typedefed enums and unnamed C enums. Let's delve into the best solutions:

X-Macros: The Champion

X-macros emerge as the top choice, offering an elegant solution:

#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;
}

The accompanying file "colours.def" holds:

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

Customizing String Output

For added flexibility, you can tweak the string output:

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

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

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