Question

我无法理解以下编译错误：

unsigned char buf[1000];
const DWORD maxBytes = 1000;
OVERLAPPED o;

void foo(DWORD dwErrorCode, DWORD dwNumberOfBytesTransfered, LPOVERLAPPED lpOverlapped) {
  return;
}

void bar(HANDLE hFile) {
  auto lambda_foo = [](DWORD dwErrorCode, DWORD dwNumberOfBytesTransfered, LPOVERLAPPED lpOverlapped){return;};
  ReadFileEx(hFile, buf, 1000, &o, lambdafoo); //compiles
  ReadFileEx(hFile, buf, 1000, &o, foo); //doesn't compile
}

错误是“无法将参数5从'void（__ cdecl *）DWORD，DWORD，LPOVERLAPPED''转换为'LPOVERLAPPED_COMPLETION_ROUTINE'”。我使用的是MSVC2015。

有人可以告诉我我做错了什么吗？为什么它与lambda编译但没有相同的自由函数？

Answer 1

Windows中的回调对调用约定有特殊要求。 Windows提供了一个方便的宏CALLBACK，用于在定义函数时指定调用约定

void CALLBACK foo(DWORD dwErrorCode, DWORD dwNumberOfBytesTransfered, LPOVERLAPPED lpOverlapped)
{
  return;
}

使用自由函数作为LPOVELAPPED_COMPLETION_ROUTINE

1 个答案: