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[英]'System.EntryPointNotFoundException' when trying to call unmanaged function from C#
[英]System.EntryPointNotFoundException when calling C++ code from C#
// ------------------------------------- C#Code --------- ---------------------------
[DllImport("MarshallStringsWin32.dll", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
extern static void Test([MarshalAs(UnmanagedType.AnsiBStr)] out String str);
[DllImport("MarshallStringsWin32.dll", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
extern static void FreeString([MarshalAs(UnmanagedType.AnsiBStr)] String str);
static void Main(string[] args)
{
String str;
Test(out str);
FreeString(str);
}
// ------------------------------------- C ++代碼--------- ---------------------------
void Test(__out BSTR* str)
{
const std::string stdStr = "The quick brown fox jumps over the lazy dog";
_bstr_t bstrStr = stdStr.c_str();
*str = bstrStr.copy();
}
void FreeString(BSTR str)
{
SysFreeString(str);
}
我在調用Test()時收到System.EntryPointNotFoundException。 有人會知道我做錯了什么嗎? 這是編組字符串的正確方法嗎?
也許你需要在頭文件中添加c ++代碼的代碼:
extern "C" void __declspec(dllexport) FreeString(BSTR str);
extern "C" void __declspec(dllexport) Test(BSTR* str);
這幾乎可以肯定是因為C#不能將您的方法Test的名稱映射到本機代碼中的Test方法。 嘗試為方法指定EntryPoint =“Test”屬性,如下所示:
[DllImport("MarshallStringsWin32.dll", EntryPoint="Test", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
extern static void Test([MarshalAs(UnmanagedType.AnsiBStr)] out String str);
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