C++大学基础教程_4_8计数器控制的循环

//GradeBook.h
#include<string>
using  std::string;
 
class GradeBook
{
public:
GradeBook(string );//重载构造函数
void setCourseName(string );//设置课程名称
string getCourseName();//返回课程名称
void disPlayMessage();//欢迎信息
void determineClassAverage();//统计全班学生某一门课程的平均分以及总分
private:
string courseName;//course name for this GradeBook class
};

//GradeBook.cpp
#include<iomanip>
#include <iostream>
using namespace std;
#include "GradeBook.h"  //两个include头文件的顺序还对报错有影响额，好神奇！！！！！
GradeBook::GradeBook(string name)
{
setCourseName(name);
}
 
//进行判断，如果输入coursename字符大于25，则取前25个字符
void GradeBook::setCourseName(string name)
{
if(name.length()<=25)
courseName = name;
else 
{
courseName = name.substr(0,25);//select first 25 characters
cout << "Name\"" << name << "\"exceeds maximum length(25).\n"
  << "limiting courseName to first 25characters.\n" << endl;
}
}
 
string  GradeBook::getCourseName()
{
return courseName;
}
 
void GradeBook::disPlayMessage()
{
cout << "welcome to the grade book for\n" << getCourseName() << "!\n"<< endl;
 
}
 
void GradeBook::determineClassAverage()
{
int total = 0;//学生总成绩
int grade;//输入的学生成绩
int gradeCounter = 0 ;//输入的学生成绩个数
double average ;//学生的平均成绩
 
cout << "Enter the first grade or -1 to quit :" << endl;
cin >> grade ;
 
while(grade!=-1)
{
total = total +grade ;
gradeCounter = gradeCounter +1 ;//计数器加一
cout << "Enter the " << gradeCounter +1<< "th grade or -1 to quit :" << endl;
   cin >> grade ;
}
if(gradeCounter != 0)
{
average = static_cast<double>(total)/gradeCounter ;
cout << "\n Total of all " << gradeCounter << " grades entered is :" << total << endl;
cout << "Class average is :" << setprecision(4) << fixed << average << endl;
}
else
cout << "No grades were entered !" << endl;
 
}

// main.cpp
#include "GradeBook.h"
 
int main()
{
GradeBook myGradeBook("C++大学基础教程");
myGradeBook.disPlayMessage();
myGradeBook.determineClassAverage();
system("pause >>  cout ");
return 0;
}