是否可以从C#项目引用C++项目

Question

我正试图调用我从一些C#编写的一些C++(也是我的代码(，但在Interop/PInvoke获取已填充的int[]时遇到了问题。有没有一种方法可以让我从C#项目中添加一个对C++项目的编译时引用，并调用其中的函数，就好像它只是另一个C#类库一样？

我有一个基本的示例来说明数组的问题。这是我正在调用的C++函数的C#签名。

[DllImport("CPlusPlusTargetLibrary.dll", CallingConvention = CallingConvention.StdCall)]
private static extern void Accumulate
(
int input,
int accumulationFactor,
int numberOfAccumulations,
[In, Out, MarshalAs(UnmanagedType.LPArray)]
int[] accumulationsPointer
);

这就是从C#调用它的方式：

var numberOfAccumulations = 3;
var accumulations = new int[numberOfAccumulations];
Accumulate(-8, 1, numberOfAccumulations, accumulations);

这是它在C++头文件中的声明：

__declspec(dllexport) const void __stdcall Accumulate
(
const signed long input,
const signed long accumulationFactor,
const signed long numberOfAccumulations,
signed long* accumulationsPointer
);

这是它在C++中的实现：

__declspec(dllexport) const void __stdcall Accumulate
(
const signed long input,
const signed long accumulationFactor,
const signed long numberOfAccumulations,
signed long* accumulationsPointer
)
{
for (auto index = 0; index < numberOfAccumulations; index++, accumulationsPointer++)
{
auto accumulation = input * ((index + 1) * accumulationFactor);
accumulationsPointer = &accumulation;            
}
}

accumulations数组只是作为所有0的3元素数组返回，就像它被传入一样。相反，它应该包含-8、-16和-24。

我遵循了MSDN上关于封送int[]的文档，根据它，我不应该需要任何手动封送(但即使去掉MarshalAs属性也无法解决问题(：https://learn.microsoft.com/en-us/dotnet/framework/interop/marshaling-different-types-of-arrays

我曾希望，如果我可以直接引用C++项目，那么我就不必处理所有与类型相关的运行时故障。

Answer 1

您的代码不写入accumulationsPointer的内容，而是用accumulation的地址覆盖指针本身

---

它应该是类似于这个的东西

for (auto index = 0; index < numberOfAccumulations; index++, accumulationsPointer++)
{
auto accumulation = input * ((index + 1) * accumulationFactor);
*accumulationsPointer = accumulation;
}

---

或类似的，如c#

for (auto index = 0; index < numberOfAccumulations; ++index)
{
auto accumulation = input * ((index + 1) * accumulationFactor);   
accumulationsPointer[index] = accumulation;            
}

---

btw，signed long* accumulationsPointer也可以写成signed long accumulationsPointer[]，例如

void Accumulate
(
const signed long input,
const signed long accumulationFactor,
const signed long numberOfAccumulations,
signed long accumulations[]
)
{
for (auto index = 0; index < numberOfAccumulations; ++index)
{
auto accumulation = input * ((index + 1) * accumulationFactor);
accumulations[index] = accumulation;            
}
}