33

#include <string>
#include <iostream>
using namespace std;

class ExamInfo {
public:
//三种构造函数，分别用等级、是否通过和百分来初始化
ExamInfo(string name, char grade)
: name(name), mode(GRADE), grade(grade) { }
ExamInfo(string name, bool pass)
: name(name), mode(PASS), pass(pass) { }
ExamInfo(string name, int percent)
: name(name), mode(PERCENTAGE), percent(percent) { }
void show();

private:
string name; //课程名称
enum {
GRADE,
PASS,
PERCENTAGE
} mode; //采用何种计分方式
union {
char grade; //等级制的成绩
bool pass; //是否通过
int percent; //百分制的成绩
};
};

void ExamInfo::show() {
cout << name << ": ";
switch (mode) {
case GRADE:
cout << grade;
break;
case PASS:
cout << (pass ? "PASS" : "FAIL");
break;
case PERCENTAGE:
cout << percent;
break;
}
cout << endl;
}

int main() {
ExamInfo course1("English", 'B');
ExamInfo course2("Calculus", true);
ExamInfo course3("C++ Programming", 85);
course1.show();
course2.show();
course3.show();
return 0;
}