throw domain_error问题

[都说没想好]

题目是输入两次考试成绩和几次家庭作业成绩，按比例算出总成绩，如果家庭作业成绩没做的情况抛出异常


#include<iostream>
#include<string>
#include<stdexcept>
#include<ios>
#include<iomanip>

using std::cin;
using std::cout;
using std::endl;

int main()
{
cout<<"please enter your first name:";
std::string name;
cin>>name;
cout<<"Hello, "<<name<<"!"<<endl;

cout<<"Please enter your midterm and final exam grades:";
double midterm,final;
cin>>midterm>>final;

ut<<"Enter all your homework grades,"
"followed by end-of-file:";

int count=0;
double sum=0;

double x;
while(cin>>x)
{
++count;
sum+=x;
}

if(count==0)
throw std::domain_error ("The Student has done no homework;");
//上面这句有什么错，我这样写，运行的时候如果不输入作业成绩，直接ctrl+z会给我一个终止框，我要的是能抛出异常并且给语句提示，怎么改~
std::streamsize prec=cout.precision();

cout<<"Your final grade is"<<std::setprecision(3)
<<0.2*midterm+0.4*final+0.4*sum/count
<<std::setprecision(prec)<<endl;

return 0;
}

[buyong]

try{...
if(***)
   throw something;
....
}
catch(...)
{
}

[都说没想好]

引用 1 楼 buyong 的回复:

try{...
if(***)
   throw something;
....
}
catch(...)
{
}

可以具体给我代码吗，我试了试 try{ if(count==0) throw std::domain_error ("The Student has done no homework;"); }catch (std::domain_error){ } std::streamsize prec=cout.precision(); cout<<"Your final grade is"<<std::setprecision(3) <<0.2*midterm+0.4*final+0.4*sum/count <<std::setprecision(prec)<<endl; 结果他直接给我算了乱码答案出来了。。