Using macros to name functions in C

Question

The other day I was trying to use a macro to define a function like so (simplified, obviously):

#define DEF_ADD(name) \
    int add_name(int x, int y) { \
        return x + y; \
    } \

Now, I expected the snippet DEF_ADD(hello) to define the function add_hello . However, the macro call instead defines a function called add_name . I expect that this has something to do with scanning, but I couldn't find a way to recreate the behavior I'm looking for. Any ideas how to do this?

Answer 1

You need

#define DEF_ADD(name) \
    int add_##name(int x, int y) { \
    return x + y; \
}

Note well the ## . I've also dropped the final newline character. Else the parameter name is not used and you create add_name as the function name.