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Platform Invoke Examples

The following examples demonstrate how to define and call the MessageBox function in User32.dll, passing a simple string as an argument. In the examples, the DllImportAttribute.CharSet Field field is set to Auto to let the target platform determine the character width and string marshaling.

The same example appears in Visual Basic, C#, and C++. To show all examples, click the Language Filter button Filter2 in the upper-left corner of the page. For additional examples, see Marshaling Data with Platform Invoke.

using namespace System::Runtime::InteropServices;

typedef void* HWND;
[DllImport("user32", CharSet=CharSet::Auto)]
extern "C" IntPtr MessageBox(HWND hWnd,
                          String* pText,
                          String* pCaption,
                          unsigned int uType);
void main(void) {
     String* pText = L"Hello World!";
     String* pCaption = L"Platform Invoke Sample";
     MessageBox(0, pText, pCaption, 0);
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