Function overloading in C

add.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int addi(int a, int b) {
    return a + b;
}

char *adds(char *a, char *b) {
    char *res = malloc(strlen(a) + strlen(b) + 1);
    strcpy(res, a);
    strcat(res, b);
    return res;
}

#define add(a, b) _Generic(a, int: addi, char*: adds)(a, b)

int main(void) {
    int a = 1, b = 2;
    printf("%d\n", add(a, b)); // 3

    char *c = "hello ", *d = "world";
    printf("%s\n", add(c, d)); // hello world

    return 0;
}

Without C11:

#define NARG_(_15, _14, _13, _12, _11, _10, _9, _8, _7, _6, _5, _4, _3, _2, _1, N, ...) N
#define NARG(...) NARG_(__VA_ARGS__, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
#define PASTE(a, b) a ## b
#define XPASTE(a, b) PASTE(a, b)

int foo(int a, int b) {
    return 1;
}
#define foo2(a,b) foo((a), (b))
#define foo1(x) foo2(x,0)
#define foo(...) XPASTE(foo, NARG(__VA_ARGS__))(__VA_ARGS__)

http://stackoverflow.com/questions/479207/function-overloading-in-c/13010401#13010401

Is there a way to do stricter type checking on more than one argument? As I read this, it is only checking the type of the first argument?

1. Type checking only on one argument

2. main leaks memory

@thelonewolf https://github.com/nautical/CBullet/blob/master/pie.h

@theonewolf https://github.com/nautical/CBullet/blob/master/pie.h

@jasiek: The Arduino IDE uses C++, so function overloading works just fine. (So do templates, but you have to define them in a .h file rather than the default extension-less file.)

@KLuka
It's not good practice to not free something you've malloc'd.

Still not supported by Intel C compiler though.

@nautical Submitted: http://stackoverflow.com/a/31640391/293064

@dubslow Yes, main leaks memory. I realize now that github has its own "grammar police" since that was not the point of this gist.

@Fusion I'd say it's not github, but C community, as memory leaks is something to avoid even in examples that are this simple.

DAE notice the memory leak???????????????

OMG did you guys see the memory leak?!!

'a' gets evaluated twice

There is a memory leak. You allocate with malloc but you never free the allocated memory. You should fix that.

Who says C can't be high-level and beautiful? <3