如何:使用 C++ Interop 封送嵌入式指针
更新:2007 年 11 月
下面的代码示例使用 managed, unmanaged #pragma 指令在同一个文件中实现托管函数和非托管函数,但如果在不同的文件中定义这些函数,则它们将以同样的方式进行交互操作。不需要使用 /clr(公共语言运行库编译) 对仅包含非托管函数的文件进行编译。
示例
下面的示例演示如何从托管函数调用采用包含指针的结构的非托管函数。该托管函数创建该结构的一个实例,并使用新关键字(而不是 gcnew 关键字)对嵌入的指针进行初始化。由于是在本机堆上分配内存,因此不需要固定该数组以取消垃圾回收。但是,必须显式删除内存,以避免内存溢出。
// marshal_embedded_pointer.cpp
// compile with: /clr
#include <iostream>
using namespace System;
using namespace System::Runtime::InteropServices;
// unmanaged struct
struct ListStruct {
int count;
double* item;
};
#pragma unmanaged
void UnmanagedTakesListStruct(ListStruct list) {
printf_s("[unmanaged] count = %d\n", list.count);
for (int i=0; i<list.count; i++)
printf_s("array[%d] = %f\n", i, list.item[i]);
}
#pragma managed
int main() {
ListStruct list;
list.count = 10;
list.item = new double[list.count];
Console::WriteLine("[managed] count = {0}", list.count);
Random^ r = gcnew Random(0);
for (int i=0; i<list.count; i++) {
list.item[i] = r->NextDouble() * 100.0;
Console::WriteLine("array[{0}] = {1}", i, list.item[i]);
}
UnmanagedTakesListStruct( list );
delete list.item;
}
[managed] count = 10
array[0] = 72.624326996796
array[1] = 81.7325359590969
array[2] = 76.8022689394663
array[3] = 55.8161191436537
array[4] = 20.6033154021033
array[5] = 55.8884794618415
array[6] = 90.6027066011926
array[7] = 44.2177873310716
array[8] = 97.754975314138
array[9] = 27.370445768987
[unmanaged] count = 10
array[0] = 72.624327
array[1] = 81.732536
array[2] = 76.802269
array[3] = 55.816119
array[4] = 20.603315
array[5] = 55.888479
array[6] = 90.602707
array[7] = 44.217787
array[8] = 97.754975
array[9] = 27.370446