这个程序应该怎么改啊？求解

Question

调试下列程序,使之具有如下功能:任意输入2个数,调用两个函数分别求:
⑴ 2个数的和,
⑵ 2个数交换值.
要求用函数指针调用这两个函数,结果在主函数中输出.
main()
{
int a,b,c,(*p)();
scanf("%d,%d",&a,&b);
p=sum;
*p(a,b,c);
p=swap;
*p(a,b);
printf("sum=%d\n",c);
printf("a=%d,b=%d\n",a,b);
}
sum(int a,int b,int c)
{
c=a+b;
}
swap(int a;int b)
{
int t;
t=a;
a=b;
b=t;
}

Answer 1

#include <stdio.h>

void sum(int a, int b, int *c)
{
    *c = a + b;
}

void swap(int *a, int *b)
{
    int t;
    t = *a;
    *a = *b;
    *b = t;
}

int main()
{
    int a, b, c;
    scanf("%d,%d", &a, &b);
    void (*p1)(int, int, int *) = sum;
    p1(a, b, &c);
    void (*p2)(int *, int *) = swap;
    p2(&a, &b);
    printf("sum=%d\n", c);
    printf("a=%d,b=%d\n", a, b);
    return 0;
}