从不工作的类中的另一个文件请求函数

Question

我有两个.cpp文件，名为"FactoringProgram.cpp“和"FactoringProgram2nd.cpp"，还有一个名为"FactoringProgram.h”的头文件。我已经尝试过在StackOverflow和其他几个站点上搜索这个问题，但是没有找到对我有用的解决方案。当我试图运行以下命令："g++ FactoringProgram.cpp FactoringProgram2nd.cpp“时，会得到以下错误：

FactoringProgram.cpp:在函数‘int()’：FactoringProgram.cpp:8:11: error:对‘Problem1 1’中的成员‘InitialMessage’的请求，它是非类类型的‘Factoring()’ 问题1.()；

"FactoringProgram.h“的代码是：

#ifndef FactoringProgram_h
#define FactoringProgram_h

#include <stdio.h>
#include <iostream>

class Factoring
{
private:
    int m_FirstCoefficent;
    char m_FirstOperator;
    int m_SecondCoefficent;
    char m_SecondOperator;
    int m_3rdExpression;
public:
    Factoring();

    int InitialMessage();
};

#endif

FactoringProgram.cpp代码：

#include <stdio.h>
#include <iostream>
#include "FactoringProgramH.h"

int main()
{
    Factoring Problem1();
    Problem1.InitialMessage();
    return 0;
}

FactoringProgram2nd.cpp代码：

#include "FactoringProgramH.h"
#include <stdio.h>
#include <iostream>

    Factoring::Factoring(int FirstCoefficent=0, char FirstOperator='+',
     int SecondCoefficent=1, char SecondOperator='+', int 3rdExpression=1)
        : m_FirstCoefficent(FirstCoefficen), m_FirstOperator(FirstOperator),
    m_SecondCoefficent(SecondCoefficent), m_SecondOperator(SecondOperator),
    m_3rdExpression(3rdExpression);
    {

    }

int Factoring::InitialMessage()
{
    std::cout << "Ok right now your expression is looking like: "
        << FirstCoefficent << "x^2 " << FirstOperator << " " << SecondCoefficent
        << " x" << SecondOperator << " " << 3rdExpression;
}

Answer 1

您的代码有几个小错误。这是一个有效的版本(您可以比较并查看我需要更改的内容)。这些变动的摘要如下：

• 默认参数值应该在头文件(*.h)中；
• 不能用数字开始变量/参数名称；
• int InitialMessage()不返回任何东西，所以我将它更改为void InitialMessage()；
• 在构造函数中初始化字段时，最后一个字段不能以分号结尾；
• 修正了最令人烦恼的解析 (per @RSahu注释)在main.cpp中的问题。

FactoringProgram.h

#ifndef FactoringProgram_h
#define FactoringProgram_h

#include <stdio.h>
#include <iostream>

class Factoring
{
private:
    int m_FirstCoefficent;
    char m_FirstOperator;
    int m_SecondCoefficent;
    char m_SecondOperator;
    int m_3rdExpression;

public:
    Factoring(int FirstCoefficent = 0, char FirstOperator = '+',
              int SecondCoefficent = 1, char SecondOperator = '+', int thirdExpression = 1);

    void InitialMessage();
};

#endif

FactoringProgram.cpp

#include "FactoringProgram.h"

Factoring::Factoring(int firstCoefficent, char firstOperator, int SecondCoefficent, char SecondOperator, int thirdExpression) :
        m_FirstCoefficent(firstCoefficent),
        m_FirstOperator(firstOperator),
        m_SecondCoefficent(SecondCoefficent),
        m_SecondOperator(SecondOperator),
        m_3rdExpression(thirdExpression)
{}

void Factoring::InitialMessage()
{
    std::cout << "Ok right now your expression is looking like: "
              << m_FirstCoefficent << "x^2 " << m_FirstOperator << " " << m_SecondCoefficent
              << " x" << m_SecondOperator << " " << m_3rdExpression;
}

main.cpp

#include <stdio.h>
#include <iostream>
#include "FactoringProgram.h"

int main()
{
    Factoring Problem1;
    Problem1.InitialMessage();
    return 0;
}

Answer 2

将此错误替换为：

Factoring Problem1();

出自：

Factoring Problem1 = Factoring();

问题在于编译器将这一行解释为函数声明，而不是变量声明。正如注释中提到的，这被称为最令人烦恼的解析器问题。

您发布的代码包含了更多的小错误。

Answer 3

您应该在没有params的情况下定义Factoring()，我在FactoringProgram.h中使用了头。

FactoringProgram.h

#include <stdio.h>
#include <iostream>

class Factoring
{
private:
    int m_FirstCoefficent;
    char m_FirstOperator;
    int m_SecondCoefficent;
    char m_SecondOperator;
    int m_3rdExpression;
public:
    Factoring();
    Factoring(int,char,int,char,int);

    int InitialMessage();
};

#endif

FactoringProgram.cpp

#include "FactoringProgram.h"

int main()
{
    Factoring Problem1 = Factoring();
    Problem1.InitialMessage();
    system("pause");
    return 0;
}

FactoringProgram2nd.cpp

#include "FactoringProgram.h"

Factoring::Factoring()
{
    *this = Factoring(0, '+', 1, '+', 1);

}
Factoring::Factoring(int FirstCoefficent = 0, char FirstOperator = '+',int SecondCoefficent = 1, char SecondOperator = '+', int _3rdExpression = 1) : m_FirstCoefficent(FirstCoefficent), m_FirstOperator(FirstOperator),m_SecondCoefficent(SecondCoefficent), m_SecondOperator(SecondOperator),m_3rdExpression(_3rdExpression)
{

}

int Factoring::InitialMessage()
{
    std::cout << "Ok right now your expression is looking like: "
        << m_FirstCoefficent << "x^2 " << m_FirstOperator << " " << m_SecondCoefficent
        << " x" << m_SecondOperator << " " << m_3rdExpression;
    return 0;
}