c++ - Winapi WriteFile函数写一个字节

Question

我尝试向二进制文件写入一个字节，但获取失败...如何开始工作？

我的代码:

unsigned char b = 0x00; // equal to hex value = 00
/*
 Error: GetLastError()
 ERROR_INVALID_USER_BUFFER
 1784 (0x6F8)
 The supplied user buffer is not valid for the requested operation.
*/
WriteFile(file, ( char *)b, 1, &bytesWritten, NULL);

Answer 1

WriteFile 定义是

BOOL WINAPI WriteFile(
  _In_        HANDLE       hFile,
  _In_        LPCVOID      lpBuffer,
  _In_        DWORD        nNumberOfBytesToWrite,
  _Out_opt_   LPDWORD      lpNumberOfBytesWritten,
  _Inout_opt_ LPOVERLAPPED lpOverlapped
);

其中 lpBuffer 是指向包含要写入的数据的缓冲区的指针。

要获得指向b 的指针，您需要一个address of。运算符 & 而不是 C-style cast到字符指针:

WriteFile(file, &b, 1, &bytesWritten, NULL);