C/C++/C#使用C/C++动态链接库DLL 错误现象及解决办法图文详解

ID	Caption	命令响应函数	函数功能
IDC_BTN_ADD	Add	OnBnClickedBtnAdd	调用MyDll0.dll的add函数
IDC_BTN_SUBTRACT	Subtract	OnBnClickedBtnSubtract	调用MyDll0.dll的subtract函数

Step#3双击Add按钮添加命令响应函数

Step#4添加代码

extern "C" _declspec(dllimport) int   _stdcall  add(int a, int b);
extern "C" _declspec(dllimport) int   _stdcall  subtract(int a, int b);

void CTestDllDlg::OnBnClickedBtnAdd()
{
    // TODO: Add your control notification handler code here
    CString str;
    str.Format("5+3=%d", add(5, 3));
    MessageBox(str);
}


void CTestDllDlg::OnBnClickedBtnSubtract()
{
    // TODO: Add your control notification handler code here
    CString str;
    str.Format("5-3=%d", subtract(5, 3));
    MessageBox(str);
}

Step#5错误及解决办法

第一个错误 error C2664 cannot convert argument 1 from 'const char [7]' to 'const wchar_t *'

错误说明：error C2664: 'void ATL::CStringT<wchar_t,StrTraitMFC_DLL<wchar_t,ATL::ChTraitsCRT<wchar_t>>>::Format(UINT,...)' : cannot convert argument 1 from 'const char [7]' to 'const wchar_t *'
1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

解决办法：VS2013默认使用UNICODE编码，将其修改为Not Set

Project -> Properties -> Configuration Properties -> General -> Character Set: Not Set

第二个错误 error MSB8031: Building an MFC project for a non-Unicode character set is deprecated.

错误说明：error MSB8031: Building an MFC project for a non-Unicode character set is deprecated. You must change the project property to Unicode or download an additional library. See http://go.microsoft.com/fwlink/p/?LinkId=286820 for more information.

解决办法：
VS2013把 multi-byte character set 支持移除了

去微软网站下载这个组件就行了，网址http://go.microsoft.com/fwlink/p/?LinkId=286820

Multibyte MFC Library for Visual Studio 2013

【注意】根据自己的VS版本来选择组件，笔者的是VS2013

参考文章https://blog.csdn.net/tahelin/article/details/30312881