HOW TO：使用 C++ Interop 封送處理結構

本主題將示範 Visual C++ 互通性的一個 Facet。如需詳細資訊，請參閱使用 C++ Interop (隱含 PInvoke)。

在下列範例中，程式碼會使用 managed, unmanaged #pragma 指示詞，在相同的檔案中實作 Managed 和 Unmanaged 函式，這些函式即使在不同的檔案中定義，也會以相同的方式互相溝通。只包含 Unmanaged 函式的檔案，不需要以 /clr (Common Language Runtime 編譯) 編譯。

範例

下列程式碼範例會示範以傳值 (By Value) 和傳址 (By Reference) 的方式，從 Managed 函式將結構傳遞至 Unmanaged 函式。因為這個範例中的結構只包含簡單的內建型別 (請參閱Blittable 和非 Blittable 型別)，所以不需要特別的封送處理 (Marshaling)。若要封送處理非 Blittable 結構，例如包含指標的結構，請參閱 HOW TO：使用 C++ Interop 封送處理內嵌指標。

// PassStruct1.cpp
// compile with: /clr

#include <stdio.h>
#include <math.h>

using namespace System;
using namespace System::Runtime::InteropServices;

#pragma unmanaged

struct Location {
   int x;
   int y;
};

double GetDistance(Location loc1, Location loc2) {
   printf_s("[unmanaged] loc1(%d,%d)", loc1.x, loc1.y);
   printf_s(" loc2(%d,%d)\n", loc2.x, loc2.y);

   double h = loc1.x - loc2.x;
   double v = loc1.y = loc2.y;
   double dist = sqrt( pow(h,2) + pow(v,2) );

   return dist;
}

void InitLocation(Location* lp) {
   printf_s("[unmanaged] Initializing location...\n");
   lp->x = 50;
   lp->y = 50;
}

#pragma managed

int main() {
   Location loc1;
   loc1.x = 0;
   loc1.y = 0;

   Location loc2;
   loc2.x = 100;
   loc2.y = 100;

   double dist = GetDistance(loc1, loc2);
   Console::WriteLine("[managed] distance = {0}", dist);

   Location loc3;
   InitLocation(&loc3);
   Console::WriteLine("[managed] x={0} y={1}", loc3.x, loc3.y);
}

下列程式碼範例會示範以傳值和傳址的方式，從 Unmanaged 函式將結構傳遞至 Managed 函式。因為這個範例中的結構只包含簡單的內建型別 (請參閱Blittable 和非 Blittable 型別)，所以不需要特別的封送處理。若要封送處理非 Blittable 結構，例如包含指標的結構，請參閱 HOW TO：使用 C++ Interop 封送處理內嵌指標。

// PassStruct2.cpp
// compile with: /clr
#include <stdio.h>
#include <math.h>
using namespace System;

// native structure definition
struct Location {
   int x;
   int y;
};

#pragma managed

double GetDistance(Location loc1, Location loc2) {
   Console::Write("[managed] got loc1({0},{1})", loc1.x, loc1.y);
   Console::WriteLine(" loc2({0},{1})", loc2.x, loc2.y);

   double h = loc1.x - loc2.x;
   double v = loc1.y = loc2.y;
   double dist = sqrt( pow(h,2) + pow(v,2) );

   return dist;
}

void InitLocation(Location* lp) {
   Console::WriteLine("[managed] Initializing location...");
   lp->x = 50;
   lp->y = 50;
}

#pragma unmanaged

int UnmanagedFunc() {
   Location loc1;
   loc1.x = 0;
   loc1.y = 0;

   Location loc2;
   loc2.x = 100;
   loc2.y = 100;

   printf_s("(unmanaged) loc1=(%d,%d)", loc1.x, loc1.y);
   printf_s(" loc2=(%d,%d)\n", loc2.x, loc2.y);

   double dist = GetDistance(loc1, loc2);
   printf_s("[unmanaged] distance = %f\n", dist);

   Location loc3;
   InitLocation(&loc3);
   printf_s("[unmanaged] got x=%d y=%d\n", loc3.x, loc3.y);

    return 0;
}

#pragma managed

int main() {
   UnmanagedFunc();
}

請參閱

參考

使用 C++ Interop (隱含 PInvoke)