C++错误消息ostream未命名类型

Question

我使用 C++ 来了解类和流，但每次我尝试时都会得到错误 ostream does not name a type 我使用 std 命名空间，包括 iostream，包括 header

Uhr.cpp

#include<iostream>
#include"uhr.h"

using namespace std;

Uhr::Uhr(int Stunde, int Minute, int Sekunde){
this -> Stunde = Stunde;
this -> Minute = Minute;
this -> Sekunde = Sekunde;
}


void Uhr::setTime(int Stunde, int Minute, int Sekunde)
{
 this -> Stunde = Stunde;
 this -> Minute = Minute;
 this -> Sekunde = Sekunde;
}

void Uhr::setOne()
{
this -> Sekunde=+Sekunde;
}

ostream& Uhr::print(ostream& o)
{
o = "Stunden " << Stunden << " Minuten " << Minuten <<" Sekunden" << Sekunden;
return o:   
}

ostream& operator << (ostream &o,const Uhr& u)
{
 return u.print(o);
}

呃.h

#include<iostream>

class Uhr
{
private:
int Stunde;
int Minute;
int Sekunde;

public:
Uhr(int Stunde = 0, int Minute = 0, int Sekunde = 0);
void setTime(int Stunde, int Minute, int Sekunde);
void setOne();
ostream& print(ostream & o);
};

ostream& operator << (ostream &o,const Uhr& u);

错误: uhr.h:14:2: 错误:“ostream”没有命名类型 ostream & 打印(ostream & o)常量； ^ uhr.h:17:2: 错误:“ostream”没有命名类型 ostream& operator << (ostream &o,const Uhr& u);

Answer 1

在头文件uhr.h中，改

ostream& print(ostream & o);

到

std::ostream& print(std::ostream & o);