这个运行出来但是结果不正确的呀，怎样改啊求高手？解决方法

这个运行出来但是结果不正确的呀，怎样改啊。求高手？
#include<iostream.h>
struct student
{
float score1;
float score2;
float score3;
float score4;
double sum;
char name[20];
}stu;
void fum(student &score)
{
cout<<"输入student的名字：";
cin>>stu.name;
cout<<"输入第一次平时成绩:";
cin>>stu.score1;
cout<<"输入第二次平时成绩:";
cin>>stu.score2;
cout<<"输入期中成绩:";
cin>>stu.score3;
cout<<"输入期末成绩:";
cin>>stu.score4;

}
void main()
{
student Score;
fum(Score);
double A,B,C;
A=(Score.score1+Score.score2)*0.25;
B=Score.score3*0.25;
C=Score.score4*0.5;
Score.sum=A+B+C;
cout.setf(ios::fixed);
cout.setf(ios::showpoint);
cout.precision(3);
Score.sum=-Score.sum;
cout<<"mingziwei:"<<stu.name<<"\t"<<"得到的成绩为:"<<Score.sum<<endl;
if(Score.sum>=90)
cout<<"A"<<endl;
else if((Score.sum>=80)&&(Score.sum<90))
cout<<"B"<<endl;
else if((Score.sum>=70)&&(Score.sum<80))
cout<<"C"<<endl;
else if(Score.sum<60)
cout<<"D"<<endl;
else
cout<<"F"<<endl;
}


[解决办法]

C/C++ code

#include<iostream>using namespace std;struct student{    float score1;    float score2;    float score3;    float score4;    double sum;    char name[20];}stu;void fum(student &score){    //no stu!!!!    cout<<"输入student的名字：";    cin>>score.name;    cout<<"输入第一次平时成绩:";    cin>>score.score1;    cout<<"输入第二次平时成绩:";    cin>>score.score2;    cout<<"输入期中成绩:";    cin>>score.score3;    cout<<"输入期末成绩:";    cin>>score.score4;}int main(){    student Score;    fum(Score);    double A,B,C;    A=(Score.score1+Score.score2)*0.25;    B=Score.score3*0.25;    C=Score.score4*0.5;    Score.sum=A+B+C;    cout.setf(ios::fixed);    cout.setf(ios::showpoint);    cout.precision(3);    //Score.sum=-Score.sum;    cout<<"mingziwei:"<<stu.name<<"\t"<<"得到的成绩为:"<<Score.sum<<endl;    if(Score.sum>=90)        cout<<"A"<<endl;    else if((Score.sum>=80)&&(Score.sum<90))        cout<<"B"<<endl;    else if((Score.sum>=70)&&(Score.sum<80))        cout<<"C"<<endl;    else if(Score.sum<60)        cout<<"D"<<endl;    else        cout<<"F"<<endl;    system("pause");    return 0;}/*#include <iostream>#include <string>#include <fstream>using namespace std;int main(int argc, char **argv){const char alp = '*';string filePath  = "a.txt";system("pause");return 0;}*/