#include
 fun (int x)
{
    int n,s1,s2,s3,t;
    n=0;t=100;
    while(t<=999){
        s1=t%10;s2=s1%10;s3=t/100;
        if(s1+s2+s3==x)
        {
            printf("%d",t);
            n++;
        }
        t++;
    }
    return n;
}
main()
{    int x=-1;
    while(x<0)
    {
        printf("Plrase input(x>0:");
        scanf("%d",&x);
    }
    printf("\The result is:%D\n",fun(x));
}
[Error] D:\360data\重要数据\我的文档\C-Free\Temp\未命名2.cpp:3: error: ISO C++ forbids declaration of `fun' with no type
怎么

#include<stdio.h>
int fun

返回值类型呀

你把程序的基本东西先写的全一点儿，开头就差东西