C++ Unresolved token 问题

Question

我正在为一个类(class)做一个程序，老师给了我们一个我们必须实现的Cpp文件。除了 Main 之外，所有内容都是他写的，但我遇到了一个奇怪的错误。任何帮助都会很棒。这是我的代码。

// **************************************************************************
//
// Counter.cpp
//
// Defines and tests class CounterType, which is used to count things.
// CounterType contains both a default constructor and a constructor that
// sets the count to a specified value, plus methods to increment, decrement,
// return, and output the count.  The count is always nonnegative.
//
// **************************************************************************
#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;

class CounterType
{
public:
    CounterType();
    //Initializes the count to 0.

    CounterType(int initCount);
    //Precondition: initCount holds the initial value for the count.
    //Postcondition:
    //  If initCount > 0,initializes the count to initCount.
    //  If initCount <= 0,initializes the count to 0.

    void increment();
    //Postcondition:
    //  The count is one more than it was.

    void decrement();
    //Postcondition:
    //  If the count was positive, it is now one less than it was.
    //  If the count was 0, it is still 0

    int getCount();
    void output(ostream& outStream);
    //Precondition: outStream is ready to write to
    //Postcondition: count has been written to outStream

private:
    int count;

};

 void increment();
 void decrement();
 int getCount();
 void output(ostream& outStream);

 int main()
{
    CounterType Test;

    increment();
    decrement();
    getCount();

}

CounterType::CounterType()
{
    count = 0;
}

CounterType::CounterType(int initCount)
{
    if (initCount >= 0)
        count = initCount;
    else
        count = 0;
}

void CounterType::increment()
{
    count++;
}

void CounterType::decrement()
{
    if (count > 0)
        count--;
}

int CounterType::getCount()
{
    return count;
}

void CounterType::output(ostream& outStream)
{
    outStream << count;
}

这里是错误。

Error 1 error LNK2028: unresolved token (0A000330) "void __cdecl decrement(void)" (?decrement@@$$FYAXXZ) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ)J:\MCM 10.05\MCM 10.05\MCM10.obj MCM 10.05

Answer 1

您正在声明您从未定义的全局函数 increment()、decrement() 和 getCount()。您会收到链接错误，因为您在 main() 中调用了它们，而链接器找不到它们的定义。

您可能打算调用 Counter 对象的成员函数，如下所示:

int main()
{
    CounterType Test;

    Test.increment();
    Test.decrement();
    Test.getCount();
}

如果是这种情况，您应该删除全局函数的声明:

// THESE DECLARATIONS BEFORE main() SHOULD NOT BE THERE! JUST REMOVE THEM
// void increment();
// void decrement();
// int getCount();
// void output(ostream& outStream);