Compiler Warning (level 1) C4397


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The latest version of this topic can be found at Compiler Warning (level 1) C4397.

DefaultCharSetAttribute is ignored

DefaultCharSetAttribute is ignored by the Visual C++ compiler. To specify a character set for the DLL, use the CharSet option of DllImport. For more information, see Using C++ Interop (Implicit PInvoke).

The following sample generates C4397.

// C4397.cpp  
// compile with: /W1 /c /clr  
using namespace System;  
using namespace System::Runtime::InteropServices;  
[module:DefaultCharSetAttribute(CharSet::Unicode)];   // C4397  
[DllImport("kernel32", EntryPoint="CloseHandle", CharSet=CharSet::Unicode)]   // OK  
extern "C" bool ImportDefault(IntPtr hObject);  
public ref class MySettingVC {  
   void method() {  
public ref struct StructDefault1{};  
public ref class ClassDefault1{};