#include <stdio.h>
main()
{
    int num1,num2,num3,sum,pro,sma,lar;
    float avg;
    printf("Input three diffent integers:");
    scanf("%d%d%d",&num1,&num2,&num3);
    if(num1>num2)
    {
        lar=num1;
        if(lar<num3)
    {
        lar=num3;
    }
    }
    else
    {
        sma=num2;
        if(sma>num3)
    {
        sma=num3;
    }
    }
    sum=num1+num2+num3;
    avg=sum/3;
    pro=num1*num2*num3;
    printf("Sum is %d\nAverage is %f\nProduct is %d\nSmallest is %d\nLargest is %d\n",sum,avg,pro,sma,lar);
}
其实这是一道作业题 输入3数 输出最大 最小 和 平均数还有积，可我这样编了后 执行的时候老是提示我有错误，百思不得其解，希望知道的人指点一下 谢谢！

你的程序我改了一下,现在运行的应该是正确的，就是麻烦点 ：
#include <stdio.h>
void main()
{
    int num1,num2,num3,sum,pro,sma,lar;
    float avg;
    printf("Input three diffent integers:\n");
    scanf("%d,%d,%d",&num1,&num2,&num3);
    if(num1>num2)
    {
        lar=num1;
        sma=num2;
        if(lar<num3)
        {
            lar=num3;
        }
        else
        {
            if(num2>num3)sma=num3;
            
        }
    }
    else
    {
        lar=num2;
        sma=num1;
        if(lar<num3)
        {
            lar=num3;
        }
        else
        {
            if(num1>num3)sma=num3;
            
        }
    }
    sum=num1+num2+num3;
    avg=sum/3;
    pro=num1*num2*num3;
    printf("Sum is %d\nAverage is %f\nProduct is %d\nSmallest is %d\nLargest is %d\n",sum,avg,pro,sma,lar);
}

交换数值比较用指针吧，不过我后面指针还看得不是很精通，暂时帮不了你了

#include <stdio.h>
main()
{
    int num1,num2,num3,sum,pro,max,min;
    float avg;
    printf("Input three diffent integers:");
    scanf("%d%d%d",&num1,&num2,&num3);
    if(num1>num2)
    {
        max=num1;
        min=num2;
        if(max<num3)
            max=num3;
        if(min>num3)
            min=num3;
    }
    else 
    {
        max=num2;
        min=num1;
        if(max<num3)
           max=num3;
        if(min>num3)
            min=num3;
    }
    sum=num1+num2+num3;
    avg=sum/3;
    pro=num1*num2*num3;
    printf("Sum is %d\nAverage is %f\nProduct is %d\nMAX is %d\nMIN is %d\n",sum,avg,pro,max,min);

}

if(num1>num2)
{
    lar=num1;
    if(lar<num3)
    {
        lar=num3;
    }
}
else 
{
    sma=num2;
    if(sma>num3)
    {
        sma=num3;
    }
}

这个求最大,最小值的算法错了.

#include <stdio.h>
int main(void)
{
    int num1,num2,num3,sum,pro,sma,lar;
    float avg;
    printf("Input three diffent integers:");
    scanf("%d%d%d",&num1,&num2,&num3);
    if(num1>num2)
    {
        lar=num1;
        sma=num2;
    }
    else 
    {
        lar=num2;
        sma=num1;
    }
    if(lar<num3)
         lar=num3;
    if(sma>num3)
         sma=num3;

    sum=num1+num2+num3;
    avg=sum/3;
    pro=num1*num2*num3;
    printf("Sum is %d\nAverage is %f\nProduct is %d\nSmallest is %d\nLargest is %d\n",sum,avg,pro,sma,lar);
    return 0;
}

[[it] 本帖最后由 xxwpk007 于 2008-10-18 21:14 编辑 [/it]]

楼主的花括号乱用的吧，不是复合语句，单语句你也用。（虽然单句也能用）
但是会看的迷糊。
，估计错在括号上。

if else的语句明显错了。

//下面是正确的
#include <stdio.h>
void main()
{
    int num1,num2,num3,sum,pro,sma,lar;
    float avg;
    printf("Input three diffent integers:");
    scanf("%d%d%d",&num1,&num2,&num3);
    if(num1>num2)
     {
        lar=num1;
        if(lar<num3)
       {
    lar=num3;
        sma=num2;
       }
    if(num2>num3)
      sma=num3;
    else
          sma=num2;
     }
    else
     {
        sma=num1;
        if(sma>num3)
       {
    sma=num3;
        lar=num2;
       }
        if(num2<num3)
     lar=num3;
    else
         lar=num2;
     }
    sum=num1+num2+num3;
    avg=sum/3.0;
    pro=num1*num2*num3;
    printf("Sum is %d\nAverage is %f\nProduct is %d\nSmallest is %d\nLargest is %d\n",sum,avg,pro,sma,lar);
}

　注意了，那个avg是平均数为浮点型，如果用整型／整型，那么结果为也为整型，所以要改成：整型／3.0结果才为float

恩， 我也是刚学习，用英文版教材彻底把我搞晕了~ 今天才有时间上，恩我再回去调试调试，再把正确代码发上来嘛~~谢谢各位了！！ 非常感谢！