c++ - 不能使用隐式链接的 .dll 中的类

Question

我在 ShapeTester.cpp(另一个 .dll 项目)中使用 Shape.dll 中的类 Shape 时遇到问题。

//Shape.h

#ifdef SHAPE_EXPORTS
#define SHAPE_API __declspec(dllexport)

class SHAPE_API Shape
{
public:
Shape();
Shape(int sides, int sideLength, int apothem);
~Shape();

int Perimeter();
double Area();
private:
int sides;
int sideLength;
int apothem;
};
#endif

------------------------------------------------------------
//Shape.cpp

#include "stdafx.h"
#include "Shape.h"

Shape::Shape() : sides(0), sideLength(0), apothem(0)
{
}

Shape::Shape(int sides, int sideLength, int apothem) : sides(sides), sideLength(sideLength), apothem(apothem)
{
}

Shape::~Shape()
{
}

double Shape::Area()
{
    //implementation
}

int Shape::Perimeter()
{
    //implementation
}

-----------------------------------------------------------
//ShapeTester.cpp (this is in another DLL project)
#include "stdafx.h"
#include "ShapesTester.h"
#include "Shape.h"

bool ShapesTester::Test()
{
    Shape myShape = Shape(3, 9, 5); // error here; cant resolve symbol Shape

    return myShape.Area() == 67.5;
}

我在预处理器指令中包含了 SHAPE_EXPORT，我可以获得 .dll、.lib

属性 > 配置属性 > 链接器 > 输入 > 将附加依赖项设置为 Shape.lib

Properties > configuration Properties > Linker > General> Additional Library Directories(指向 Shape.Lib 的位置)

Properties > configuration Properties > C/C++ > Additional Include Directories(指向 Shape.h 的位置)

Answer 1

您的Shape 类应该在#ifdef block 之外，而不是在其中。除非定义了 SHAPE_EXPORT 符号，否则代码不会声明 Shape 类。

你想做的是

#ifdef SHAPE_EXPORTS
#define SHAPE_API __declspec(dllexport)
#else
#define SHAPE_API __declspec(dllimport)
#endif

class SHAPE_API Shape
// etc