3 文件项目中的 c++ 命名空间未定义引用

Question

我正在学习 Stephen Prata 的 C++ Primer。我刚刚了解到名称空间的概念。我创建了一个简单的三文件项目来实现我的命名空间。我还没有实现太多代码，但足以编译。但是，我收到以下错误：对 `SALES::setSales(SALES::Sales&, double const*, int)' 的未定义引用。我想我没有 declared/included 正确的东西。这是我的三个文件。请帮助并提前感谢您阅读本文。

//sales.h

#ifndef SALES_H_
#define SALES_H_

namespace SALES
{
    const int QUARTERS = 4;
    struct Sales
    {
        double sales[QUARTERS];
        double average;
        double max;
        double min;
    };
    // copies the lesser of 4 or n items from the array ar
    // to the sales member of s and computes and stores the
    // average, maximum, and minimum values of the entered items;
    // remaining elements of sales, if any, set to 0
    void setSales(Sales & s, const double ar[], int n);

    // gathers sales for 4 quarters interactively, stores them
    // in the sales member of s and computes and stores the
    // average, maximum, and minimum values
    void setSales(Sales & s);

    // display all information in structure s
    void showSales(const Sales & s);

}

#endif

//sales.cpp

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

// copies the lesser of 4 or n items from the array ar
// to the sales member of s and computes and stores the
// average, maximum, and minimum values of the entered items;
// remaining elements of sales, if any, set to 0
void setSales(SALES::Sales & s, const double ar[], int n)
{

}
// gathers sales for 4 quarters interactively, stores them
// in the sales member of s and computes and stores the
// average, maximum, and minimum values
void setSales(SALES::Sales & s)
{

}
// display all information in structure s
void showSales(const SALES::Sales & s)
{

}

//main.cpp
#include <iostream>
#include "sales.h"
using namespace std;
using namespace SALES;

int main()
{
    Sales Bill;
    const double Bill_sales[] = {1200.23,1400.01,2357.45,4530.58};
    setSales(Bill,Bill_sales,QUARTERS);
    Sales Mary;
    setSales(Mary);

    return 0;
}

Answer 1

呃，尝试将 SALES:: 添加到函数中。例如，

void SALES::setSales(SALES::Sales & s) { }

3 文件项目中的 c++ 命名空间未定义引用

c++ namespaces in a 3 file project undefined reference

c++

namespaces