#include <iostream>
using namespace std;

struct Studentrecord
{
int student_number;
int s_1,s_2,s_m,s_t;
char grade;
};
void get_input(Studentrecord& the_student);

double score(Studentrecord& thestudent);

char grade(double score);

void get_input(Studentrecord the_student)
{
cout<<"-------------"<<endl;
cin>>Studentrecord.student_number;
cout<<"-------------"<<endl;
cin>>Studentrecord.s_1;
cout<<"-------------"<<endl;
cin>>Studentrecord.s_2;
cout<<"-------------"<<endl;
cin>>Studentrecord.s_m;
cout<<"-------------"<<endl;
cin>>Studentrecord.s_t;
}

double score(Studentrecord& thestudent)
{
int rate1=50,rate2=25;
double percent1,percent2;
percent1=rate1/100;
percent2=rate2/100;
return(score=(Studentrecord.s_t)*percent1+(Studentrecord.s_m)*percent2+(Studentrecord.s_1+Studentrecord.s_2)*5*percent2);
}
char grade(double score)
{
if(score>=90) return 'A';
else if(score>=80) return 'B';
else if(score>=70) return 'C';
else if(score>=60) return 'D';
else return 'F';
}

int main()
{
Studentrecord student;
char ans;
do
{
get_input(student);
score1=score(student);
grade1=grade(score);

cout<<score1<<endl;
cout<<grade1<<endl;
cin>>ans;
}while(ans=='y'||ans=='Y');

return 0;
}

#include <iostream>
using namespace std;

struct Studentrecord
{
int student_number;
int s_1,s_2,s_m,s_t;
char grade;
};
void get_input(Studentrecord& the_student);

double score(Studentrecord& thestudent);

char grade(double score);


void get_input(Studentrecord& the_student)
{
cout<<"-------------"<<endl;
cin>>the_student.student_number;
cout<<"-------------"<<endl;
cin>>the_student.s_1;
cout<<"-------------"<<endl;
cin>>the_student.s_2;
cout<<"-------------"<<endl;
cin>>the_student.s_m;
cout<<"-------------"<<endl;
cin>>the_student.s_t;
}

double score(Studentrecord& thestudent)
{
int rate1=50,rate2=25;
double percent1,percent2;
percent1=rate1/100;
percent2=rate2/100;
return (thestudent.s_t)*percent1+(thestudent.s_m)*percent2+(thestudent.s_1+thestudent.s_2)*5*percent2;
// return score;
}
char grade(double score)
{
if(score>=90) return 'A';
else if(score>=80) return 'B';
else if(score>=70) return 'C';
else if(score>=60) return 'D';
else return 'F';
}

int main()
{
Studentrecord student;
double score1;
char grade1;
char ans;
do
{
get_input(student);
score1 = score(student);
grade1 = grade(score1);

cout<<score1<<endl;
cout<<grade1<<endl;
cin>>ans;
}while(ans=='y'||ans=='Y');

return 0;
}

语法没错了
但是－－结果计算不对……

double score(Studentrecord& thestudent)
{
int rate1=50,rate2=25;
double percent1,percent2;
percent1=rate1/100;
percent2=rate2/100;
return (thestudent.s_t)*percent1+(thestudent.s_m)*percent2+(thestudent.s_1+thestudent.s_2)*5*percent2;
｝

这里有问题……
double score(Studentrecord& thestudent)
{
double rate1=50,rate2=25;
double percent1,percent2;
percent1=rate1/100;
percent2=rate2/100;
return （(thestudent.s_t)*percent1+(thestudent.s_m)*percent2+(thestudent.s_1+thestudent.s_2)*5*percent2）;
｝

知道了 写到头晕那么简单的错都看不出来了
谢谢咯