我是C ++编码的初学者,我有一个关于从文件读取特定类对象的行的问题,其中一个是数组。
我的班级对象:
const int SIZE_OF = 5;
class Student
{
public:
Student();
Student(const Student &);
Student(string, int, int, int, int, int);
friend std::istream& operator >> (std::istream& in, Student& S);
void display();
private:
string lastName;
int grades[SIZE_OF];
};
用于定义功能的CPP文件:
Student::Student()
{
int i;
string lastName = "default";
for (i = 0; i < 5; i++)
{
grades[i] = 0;
}
}
Student::Student(const Student & S)
{
int i;
lastName = S.lastName;
for (i = 0; i < 5; i++)
{
grades[i] = S.grades[i];
}
}
Student::Student(string S, int a, int b, int c, int d, int e)
{
lastName = S;
grades[0] = a;
grades[1] = b;
grades[2] = c;
grades[3] = d;
grades[4] = e;
}
std::istream& operator >> (std::istream& in, Student& S)
{
std::string line;
std::getline(in, line);
in >> S.lastName >> S.grades[0] >> S.grades[1] >> S.grades[2] >> S.grades[3] >> S.grades[4];
getline(in, S.lastName);
return in;
}
void Student::display()
{
int i;
int sum = 0;
double average;
cout << "Last Name: " << lastName << endl;
cout << "Grades: " << endl;
for (i = 0; i < 5; i++)
{
cout << grades[i] << endl;
}
for (i = 0; i < 5; i++)
{
sum = sum + grades[i];
}
average = sum / 5;
cout << "Average: " << average;
}
我需要做的是从文件中读取并将名称保存在lastName
类的Student
对象下。然后我需要保存数组对象中的每个等级。然后我需要为下一个名称创建一个新的Student
类对象,并为4个名称重复该过程。我正在阅读的文件:
George
75,85,95,100,44
Peter
100,100,100,100,100
Frank
44,55,66,77,88
Alfred
99,88,77,66,55
答案 0 :(得分:1)
您的以下功能似乎有误:
std::istream& operator >> (std::istream& in, Student& S)
{
std::string line;
std::getline(in, line);
in >> S.lastName >> S.grades[0] >> S.grades[1] >> S.grades[2] >> S.grades[3] >> S.grades[4];
getline(in, S.lastName);
return in;
}
你读了两次lastName,你不要忽略&#39;,&#39;性格......尝试这样的事情:
std::istream& operator >> (std::istream& in, Student& S)
{
char dummy;
in >> S.lastName >> S.grades[0]
>> dummy >> S.grades[1]
>> dummy >> S.grades[2]
>> dummy >> S.grades[3]
>> dummy >> S.grades[4];
return in;
}
更新: 如果考虑lastName中的空格,则必须更改第一行以使用std :: getline,如下所示:
std::istream& operator >> (std::istream& in, Student& S)
{
char dummy;
std::getline(in, S.lastName)
in >> S.grades[0]
>> dummy >> S.grades[1]
>> dummy >> S.grades[2]
>> dummy >> S.grades[3]
>> dummy >> S.grades[4];
in.ignore(); // remove last '\n'
return in;
}
然后:
int main()
{
Student s;
std::vector<Student> all;
while (cin>>s)
all.push_back(s);
}
......还有......足够的更新!