面试题 - 用纯C语言实现支持多种数据类型（包括用户自定义类型）的加减计算器（C语言泛型）

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

// 内置类型
int addint(int a, int b) { return a+b;};
long addlong(long a, long b) { return a+b;};

// 自定义类型
typedef struct _mytype {
    int m;
}mytype;
mytype* addmytype(mytype* a, mytype* b) {
    mytype* res = (mytype*) malloc(sizeof(mytype));
    res->m = a->m + b->m;
    return res;
}

#define _add(T,a,b) add##T(a, b)
#define ADD(a,b) _Generic((a), \
    int: _add(int, a, b), \
    long: _add(long, a, b), \
    mytype*: _add(mytype, a, b), \
    default: printf("error: unknown type")\
)

int main() {
    int a=1, b=2;
    int c = ADD(a,b);
    printf("int 1+2=%d\n", c);

    long a1=3, b1=4;
    printf("long 3+4=%ld\n", ADD(a1,b1));

    mytype a2, b2;
    a2.m = 5;
    b2.m = 6;
    mytype *c2 = ADD(&a2, &b2);
    printf("mytype 5+6=%d\n", c2->m);
}

_Generic 参考：https://blog.csdn.net/qq_37151416/article/details/113203701

标签：面试题,自定义,int,ADD,long,C语言,add,printf,mytype
来源： https://www.cnblogs.com/lihuifeng/p/16439304.html