错误：“的Imag”没有指定类型

Question

我是一个新手，C++和我写一个程序添加两个复数：

这里是我的.h文件：

#ifndef IMAGINE_H 
#define IMAGINE_H 

#include<iostream> 
using std::ostream; 

class Imag{ 
public: 
    double real; 
    double imag; 

    Imag() = default; 
    Imag(double,double); 

    Imag add(Imag); 
}; 

#endif 

和这里是我的.cpp文件：

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

Imag::Imag(){ 
    this-> real; 
    this-> imag; 

} 
Imag Imag:: add(Imag i){ 
    Imag result = new Image(); 
    result -> real = this->real + i -> real; 
    result -> imag = this-> imag + i-> imag; 
    return result; 
} 

编译时，它抱怨是这样的：

imagine.cpp:5:1: error: ‘Imag’ does not name a type 
Imag::Imag(){ 
^ 
imagine.cpp:10:1: error: ‘Imag’ does not name a type 
Imag Imag:: add(Imag i){ 
^ 

有人可以帮我吗？非常感谢！

Answer 1

您没有用分号结束类声明。这是正确的语法。

class ClassName { /* */ };

Answer 2

我无法重现的问题，我得到不同的错误：

$ cat imagine.h 
#ifndef IMAGINE_H 
#define IMAGINE_H 

#include<iostream> 
using std::ostream; 

class Imag{ 
public: 
    double real; 
    double imag; 

    Imag() = default; 
    Imag(double,double); 

    Imag add(Imag); 
}; 

#endif 
$ cat imagine.cpp 
#include<iostream> 
#include"imagine.h" 
using namespace std; 

Imag::Imag(){ 
    this-> real; 
    this-> imag; 

} 
Imag Imag:: add(Imag i){ 
    Imag result = new Image(); 
    result -> real = this->real + i -> real; 
    result -> imag = this-> imag + i-> imag; 
    return result; 
} 
$ g++ -c -W -Wall -s -O2 imagine.cpp 
In file included from imagine.cpp:2: 
imagine.h:12: warning: defaulted and deleted functions only available with -std=c++0x or -std=gnu++0x 
imagine.cpp: In constructor ‘Imag::Imag()’: 
imagine.cpp:6: warning: statement has no effect 
imagine.cpp:7: warning: statement has no effect 
imagine.cpp: In member function ‘Imag Imag::add(Imag)’: 
imagine.cpp:11: error: expected type-specifier before ‘Image’ 
imagine.cpp:11: error: conversion from ‘int*’ to non-scalar type ‘Imag’ requested 
imagine.cpp:11: error: expected ‘,’ or ‘;’ before ‘Image’ 
imagine.cpp:12: error: base operand of ‘->’ has non-pointer type ‘Imag’ 
imagine.cpp:12: error: base operand of ‘->’ has non-pointer type ‘Imag’ 
imagine.cpp:13: error: base operand of ‘->’ has non-pointer type ‘Imag’ 
imagine.cpp:13: error: base operand of ‘->’ has non-pointer type ‘Imag’ 

这里是如何解决这些问题：

$ cat imagine.h 
#ifndef IMAGINE_H 
#define IMAGINE_H 

#include<iostream> 
using std::ostream; 

class Imag{ 
public: 
    double real; 
    double imag; 

    Imag(); 
    Imag(double,double); 

    Imag add(Imag); 
}; 

#endif 
$ cat imagine.cpp 
#include<iostream> 
#include"imagine.h" 
using namespace std; 
Imag::Imag(): real(0), imag(0) {} 
Imag::Imag(double r, double i): real(r), imag(i) {} 
Imag Imag::add(Imag i){ 
    Imag result; 
    result.real = real + i.real; 
    result.imag = imag + i.imag; 
    return result; 
} 
$ g++ -c -W -Wall -s -O2 imagine.cpp 
(No errors or warnings.) 

还有许多其他的方法来改善代码，例如，add可能需要代替const Imag&，而我们不需要#include <iostream>或using namespace std;。将real和imag隐藏起来也是一个好主意，并介绍公开阅读器的方法。