Visual Studio 2019：创建动态DLL库

Myth丶恋晨 2023-07-15 11:20 22阅读 0赞

# 前提 #

> [在 Visual Studio 中安装“使用 C++ 的桌面开发”工作负载][Visual Studio _ C_]

# 创建 #

1、在菜单栏上，选择“文件”>“新建”>“项目”，打开“创建新项目”对话框 。  
![在这里插入图片描述][20210113114312597.png]

2、在对话框顶部，将“语言” 设置为“C++” ，将“平台” 设置为“Windows” ，并将“项目类型” 设置为“库” 。

选中“动态链接库”，名称为“MathLibrary”

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创建解决方案后，就可以在 Visual Studio 中的“解决方案资源管理器”窗口中看到生成的项目和源文件了 。

![在这里插入图片描述][20210113114604566.png]

# 将头文件添加到 DLL #

1、若要为函数创建头文件，请在菜单栏上选择“项目” > “添加新项” 。

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 2]  
2、在“添加新项”对话框的左窗格中，选择“Visual C++” 。 在中间窗格中，选择 “头文件(.h)” 。 指定 ·MathLibrary.h 作为头文件的名称 。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 3]  
3、MathLibrary.h内容如下：

// MathLibrary.h - Contains declarations of math functions
    #pragma once
    
    #ifdef MATHLIBRARY_EXPORTS
    #define MATHLIBRARY_API __declspec(dllexport)
    #else
    #define MATHLIBRARY_API __declspec(dllimport)
    #endif
    
    // The Fibonacci recurrence relation describes a sequence F
    // where F(n) is { n = 0, a
    //               { n = 1, b
    //               { n > 1, F(n-2) + F(n-1)
    // for some initial integral values a and b.
    // If the sequence is initialized F(0) = 1, F(1) = 1,
    // then this relation produces the well-known Fibonacci
    // sequence: 1, 1, 2, 3, 5, 8, 13, 21, 34, ...
    
    // Initialize a Fibonacci relation sequence
    // such that F(0) = a, F(1) = b.
    // This function must be called before any other function.
    extern "C" MATHLIBRARY_API void fibonacci_init(
    	const unsigned long long a, const unsigned long long b);
    
    // Produce the next value in the sequence.
    // Returns true on success and updates current value and index;
    // false on overflow, leaves current value and index unchanged.
    extern "C" MATHLIBRARY_API bool fibonacci_next();
    
    // Get the current value in the sequence.
    extern "C" MATHLIBRARY_API unsigned long long fibonacci_current();
    
    // Get the position of the current value in the sequence.
    extern "C" MATHLIBRARY_API unsigned fibonacci_index();

# 向 DLL 添加实现 #

1、在“解决方案资源管理器”中，右键单击“源文件”节点并选择“添加” > “新建项目” 。 使用上一步中添加新头文件的相同方式，创建名为 MathLibrary.cpp 的新 .cpp 文件 。  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 4]  
2、MathLibrary.cpp内容为

// MathLibrary.cpp : Defines the exported functions for the DLL.
    #include "pch.h" // use stdafx.h in Visual Studio 2017 and earlier
    #include <utility>
    #include <limits.h>
    #include "MathLibrary.h"
    
    // DLL internal state variables:
    static unsigned long long previous_;  // Previous value, if any
    static unsigned long long current_;   // Current sequence value
    static unsigned index_;               // Current seq. position
    
    // Initialize a Fibonacci relation sequence
    // such that F(0) = a, F(1) = b.
    // This function must be called before any other function.
    void fibonacci_init(
        const unsigned long long a,
        const unsigned long long b)
    {
        
        index_ = 0;
        current_ = a;
        previous_ = b; // see special case when initialized
    }
    
    // Produce the next value in the sequence.
    // Returns true on success, false on overflow.
    bool fibonacci_next()
    {
        
        // check to see if we'd overflow result or position
        if ((ULLONG_MAX - previous_ < current_) ||
            (UINT_MAX == index_))
        {
        
            return false;
        }
    
        // Special case when index == 0, just return b value
        if (index_ > 0)
        {
        
            // otherwise, calculate next sequence value
            previous_ += current_;
        }
        std::swap(current_, previous_);
        ++index_;
        return true;
    }
    
    // Get the current value in the sequence.
    unsigned long long fibonacci_current()
    {
        
        return current_;
    }
    
    // Get the current index position in the sequence.
    unsigned fibonacci_index()
    {
        
        return index_;
    }

3、若要验证到目前为止是否一切正常，请编译动态链接库：请在菜单栏上选择**生成”> 生成解决方案。**

*  DLL 和相关编译器输出放在解决方案文件夹正下方的“Debug”文件夹中
 *  如果创建发布版本，该输出会放置在“Release”文件夹中  
    ![在这里插入图片描述][20210113115251393.png]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70 5]

[Visual Studio _ C_]: https://blog.csdn.net/zhizhengguan/article/details/112530889
[20210113114312597.png]: /images/20230528/35aa4562e5d94889b6416bd82a98e12b.png
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[20210113115251393.png]: /images/20230528/f892b12b86c34e308417237ca8eefe4b.png
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