Question

尝试实现简单的getter和setter函数，但编译器说当我运行getters / setter时我的变量没有在范围中定义。所以我添加了Course :: getID（）因为也许我无法访问它们的原因是因为它们被设置为私有。但后来它说原型不匹配。那么我去了头文件并更改了类似于CPP文件的原型。然后它给了我错误：额外的资格＆＃39;课程::＆＃39;在成员getID（）;任何建议？

HEADER FILE

#ifndef COURSE_H
#define COURSE_H

#include <iostream>
#include <string.h>

const unsigned CourseNameSize = 10;

class Course {
public:
  Course();
  Course( const char * nam, char ID, unsigned cred );

  char getName() const;
  char getID() const;
  unsigned GetCredits() const;


  void setName( char name );
  void SetCredits( unsigned cred );
  void setID( char ID );

  friend std::ostream & operator <<( std::ostream & os, const Course & C );
  friend std::istream & operator >>( std::istream & input, Course & C );

private:
  char name[CourseNameSize];
  char ID;
  int  credits;
};



inline unsigned Course::GetCredits() const
{
  return credits;
}

inline void Course::SetCredits( unsigned cred )
{
  credits = cred;
}

CPP文件

#include "course.h"
using namespace std;

 Course::Course()
 {
   name[0] = '\0'; // it is a char * string, not a C++ string object.
 }

 Course::Course( const char * nam, char ID,
            unsigned cred )
 {
   strncpy( name, nam, CourseNameSize );
   ID = ID;
  credits = cred;
 }

 istream & operator >>( istream & input, Course & C )
 {
   input >> C.name >> C.ID >> C.credits;
   return input;
 }

 ostream & operator <<( ostream & os, const Course & C )
 {
   os << "  Course:  " << C.name << '\n'
   << "  ID: " << C.ID << '\n'
   << "  Credits: " << C.credits << '\n';
  return os;
 }

 void setID(char ID) {ID =ID;}

 char getID() {return ID;}

 void setName(char name) {name = name;}

 char getName() {return name;}

 void setCredits(int credits) {credits = credits;}

 int getCredits() { return credits;}

Answer 1

这让你的程序搞砸了：

ID = ID;
name = name;
credits = credits;

你可能应该写

this->ID = ID;
this->name = name;
this->credits = credits;

在你的cpp文件中，由于getID()之类的函数是类成员，因此定义它们的正确方法是：

void Course::setID(char ID) { this_>ID = ID; }
char Course::getID() const { return this->ID; }
//                   ^^^^^

不要错过函数定义中的const说明符。这使得功能不同。

由于您正在使用类std::istream和std::ostream（及其方法），因此您需要在cpp文件中包含相关标头：

<强> course.cpp ：

#include <iostream>
#include "course.h"
using namespace std;

变量未在scope-getter / setter中声明

1 个答案: