我正在尝试调用一个函数。这些愚蠢的编译错误的原因是什么？

Question

我正在尝试运行我编写的这个 C++ 程序。我在 Visual C++ 中收到以下错误：

1>c:\users\server\desktop\problem7\problem7\main.cpp(26) : 错误 C3867: 'Payment::getamount': 函数调用缺少参数列表；使用 '&Payment::getamount' 创建指向成员的指针

1>c:\users\server\desktop\problem7\problem7\main.cpp(74) : 错误 C3867: 'cashPayment:: paymentDetails': 函数调用缺少参数列表；使用“&cashPayment:: paymentDetails”创建指向成员的指针

1>c:\users\server\desktop\problem7\problem7\main.cpp(75) : 错误 C3867: 'CreditCardPayment:: paymentDetails': 函数调用缺少参数列表；使用“&CreditCardPayment:: paymentDetails”创建指向成员的指针

代码为：

#include <iostream>
#include <cstring>
using namespace std;

class Payment
{
private: float amount;

public: Payment(float=0.0);
        void paymentDetails();
        float getamount();
        void setamount(float);
};


Payment::Payment(float a)
{
    setamount(a);
}

void Payment::setamount(float a){amount=a;}
float Payment::getamount(){return amount;}

void Payment::paymentDetails()
{
    cout<<"The amount of payment is : "<<getamount<<"$"<<endl;
}

class cashPayment: public Payment
{
public: cashPayment(float=0.0);
        void paymentDetails();
};
cashPayment::cashPayment(float a):Payment(a){};
void cashPayment::paymentDetails()
{
    cout<<"The payment in cash is : "<<getamount()<<"$"<<endl;
}

class CreditCardPayment: public Payment
{
private: char* name;
         int creditnumber;
         int day,month,year;

public: CreditCardPayment(char[]=" ",int=0, int=0, int=0, int=0 ,float=0.0);
        void paymentDetails();
};

CreditCardPayment::CreditCardPayment(char* n, int cn, int d, int m, int y, float a):Payment(a)
{
    int l=strlen(n);
    name = new char[l+1];
    strncpy(name,n,l);
    name[l]='\0';
    creditnumber=cn;
    day=d;
    month=m;
    year=y;
}
void CreditCardPayment::paymentDetails()
{
    cout<<"Credit Card Holder Information & Payment: "<<endl;
    cout<<"Name is "<<name<<endl;
    cout<<"Credit Number is "<<creditnumber<<endl;
    cout<<"Expiration Date (Day / Month / Year) is "<<day<<"/"<<month<<"/"<<year<<endl;
    //cout<<"Payment is "<<Payment::getamount()<<"$"<<endl;
}

int main()
{
    CreditCardPayment cc1("Mohammad",936623,21,9,2011,3000);
    cashPayment cp1(4500);
    cp1.paymentDetails;
    cc1.paymentDetails;

    system("pause");
    return 0;
}

Answer 1

在这里：

void Payment::paymentDetails()
{
    cout<<"The amount of payment is : "<<getamount<<"$"<<endl;
}

编译器告诉您，您可能指的是 getamount() 而不是 getamount。

此处类似：

cp1.paymentDetails;
cc1.paymentDetails;

您可能的意思是：

cp1.paymentDetails();
cc1.paymentDetails();

与其他一些语言不同，在 C++ 中，当您调用不带参数的函数时，您仍然必须在括号中提供空参数列表。

Answer 2

cp1.paymentDetails;
cc1.paymentDetails;

该错误指出“函数调用缺少参数列表”。您的函数调用确实缺少参数列表。您需要使用 () 来调用函数：

cp1.paymentDetails();
cc1.paymentDetails();

错误的后半部分显示“'&Payment::getamount' to create a point to member”，这是一个“有用”的提示如果您想获取函数的地址，则需要使用一元 & （地址）运算符。

之所以存在此提示，是因为计算非成员函数的地址不需要该运算符（为了与 C 兼容和遗留代码），但计算非静态成员的地址需要该运算符功能。