c语言有指针的原因二

#include <stdio>

void sum_diff(int n1,int n2, int sum,int diff)
{
    sum=n1+n2;
    diff=(n1>n2) ? n1-n2 : n2-n1;
}

int main(void)
{
    int na,nb;
    int wa=0,sa=0;
    
    printf("请输入两个整数");
    
    printf("整数A:");
    scanf("%d",&na);
    printf("整数B:");
    scanf("%d",&nb);
    
    sum_diff(na,nb,wa,sa); //调用后，这里的wa,sa被销毁，不复存在；另外函数返回值只能有一个，不能返回两个，所以函数返回值也解决不了 
    
    printf("%d,%d",wa,sa); //wa,sa的值都为0 
    
    return 0;
}

 

#include <stdio.h>

void sum_diff(int n1,int n2, int *sum,int *diff)
{
    *sum=n1+n2;
    *diff=(n1>n2) ? n1-n2 : n2-n1;
}

int main(void)
{
    int na,nb;
    int *wa;
    int *sa;
    wa=(int *)malloc(sizeof(int));
    sa=(int *)malloc(sizeof(int));
    
    
    printf("请输入两个整数");
    
    printf("整数A:");
    scanf("%d",&na);
    printf("整数B:");
    scanf("%d",&nb);
    
    sum_diff(na,nb,wa,sa); 
    
    printf("%d,%d",*wa,*sa); 
    free(wa);

    free(sa);

return 0; }