求输入几个数的平均值

#include 
main ()
{
    int x;
    double sum=0,aver;
    int i=0;
    scanf ("%d",&x);
    while (x!=-1)
    {
        sum+=x;
        i++;
        scanf ("%d",&x);
    }
    if(i>0)
    {
        aver=sum/i;
        printf("%.3f\n",aver);
    }

}

知识点:1、while语句格式[scanf(); while(a!=b) {scanf();}]