如何解决我将如何使用在头文件中预定义的朋友方法?
本质上,我的计算机科学老师让我使用朋友 std::ostream 方法进行输出..我已将其导入到头文件中,如下所示,但我不知道如何在学生中使用它.cpp。添加 student::ostream 不起作用。我如何能够在我的 student.cpp 中使用标头预定义方法
我的头文件
#pragma once
#include <iostream>
class student
{
public:
student();
std::string settingStudentName;
bool disiplineIssue();
// provided again so you learn this valuable override method for printing class data.
friend std::ostream& operator << (std::ostream& const student &);
private:
std::string studentName;
bool hasDisciplineIssue;
};
学生.cpp
#include "student.h"
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
student::student()
{
}
bool student::disiplineIssue()
{
// Max the random integer can go
int max = 100;
srand(time(0));
int random = rand()%max;
// bool variable for returning
bool True_or_False = false;
if (random <= 5)
{
True_or_False = true;
}
return True_or_False;
}
ostream& operator<< (ostream& output,const student& aStudent) {
output << aStudent.studentName << " ";
if (aStudent.hasDisciplineIssue) {
output << "has ";
}
else {
output << "doesn't have ";
}
output << "a discipline issue";
return output;
}
编辑: 当我前面没有 student:: 时,ostream 可以工作,但是如果我在前面添加 student::,它说它无法解析符号。我不确定没有 student:: 的那个是否使用我在头文件中定义的那个。
解决方法
我会按照以下方式进行:
- 在头文件和主文件中为函数
settingStudentName
添加主体和声明参数; - 插入正确的依赖项 (
#include
); - 添加一个
main()
驱动函数; - 此外,使用正确的语法 (
friend std::ostream& operator << (std::ostream&,const student &);
),在函数参数之间缺少逗号,
分隔符。
MWE:
#ifndef STUDENT_H_INCLUDED
#define STUDENT_H_INCLUDED
#include <iostream>
#include <string>
class student
{
public:
student();
std::string settingStudentName(const std::string&);
bool disiplineIssue();
// provided again so you learn this valuable override method for printing class data.
friend std::ostream& operator << (std::ostream&,const student &);
private:
std::string studentName;
bool hasDisciplineIssue;
};
#endif // STUDENT_H_INCLUDED
#include "student.h"
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <string>
using namespace std;
student::student()
{
}
string student::settingStudentName(const string& input)
{
studentName = input;
return input;
}
bool student::disiplineIssue()
{
// Max the random integer can go
int max = 100;
srand(time(0));
int random = rand()%max;
// bool variable for returning
bool True_or_False = false;
if (random <= 5)
{
True_or_False = true;
}
return True_or_False;
}
ostream& operator<< (ostream& output,const student& aStudent) {
output << aStudent.studentName << " ";
if (aStudent.hasDisciplineIssue) {
output << "has ";
}
else {
output << "doesn't have ";
}
output << "a discipline issue";
return output;
}
int main()
{
student Jack;
Jack.settingStudentName("Jack");
Jack.disiplineIssue();
cout << Jack << endl;
return 0;
}
输出如下:
Jack has a discipline issue
这是一个编译版本,您可以使用 https://wandbox.org/permlink/mF49xQxkXs3M7n0M
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 dio@foxmail.com 举报,一经查实,本站将立刻删除。