C/C++ Windows API——文件读写

// FileReadWriteDemo.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include <Windows.h>#include <locale.h>int main(){    //没有设置这句的话，printf中出现汉字包含后面的非汉字全部都打不出来    setlocale(LC_ALL, "chs");    BOOL ret;    LPCWSTR filePath = _T("C:\\Users\\Administrator\\Desktop\\file_demo_test.txt");    DWORD dwDesiredAccess = GENERIC_READ | GENERIC_WRITE;    DWORD dwShareMode = 0;    LPSECURITY_ATTRIBUTES lpSecurityAttributes = NULL;    DWORD dwCreationDisposition = OPEN_ALWAYS;    DWORD dwFlagsAndAttributes = FILE_ATTRIBUTE_NORMAL;    HANDLE hTemplateFile = NULL;    HANDLE handle = CreateFile(filePath, dwDesiredAccess, dwShareMode, lpSecurityAttributes, dwCreationDisposition, dwFlagsAndAttributes, hTemplateFile);    if (handle == NULL) {        printf("CreateFile fail(%ld)", GetLastError());    }    else {        DWORD len;        TCHAR *writeBuf = L"Win32 API 你好";        TCHAR readBuf[1024];        /*        ASCII:不加前缀（如果写入unicode字符串读出来会是乱码）        Unicode:0xFEFF        UTF8:0xEFBBBF        注意写入后用十六进制编辑器查看高低位是互换的（因为C是小端编码）        */        WORD prefix = 0xFEFF;        /*        BOOL WriteFile(        HANDLE  hFile,//文件句柄        LPCVOID lpBuffer,//数据缓存区指针        DWORD   nNumberOfBytesToWrite,//你要写的字节数        LPDWORD lpNumberOfBytesWritten,//用于保存实际写入字节数的存储区域的指针        LPOVERLAPPED lpOverlapped//OVERLAPPED结构体指针        );        return 失败返回0,成功返回非0        */        ret = WriteFile(handle, &prefix, 2, &len, NULL);        if (ret == 0) {            printf("WriteFile prefix fail(%ld)\n", GetLastError());        }        else {            printf("WriteFile prefix -> writeLen=%d\n", len);        }        /*        把写缓冲区中的数据实际写入到文件中        WINBASEAPI BOOL WINAPI FlushFileBuffers(_In_ HANDLE hFile);        return 失败返回0, 成功返回非0        */        ret = FlushFileBuffers(handle);        if (ret == 0) {            printf("FlushFileBuffers fail(%d)\n", GetLastError());        }        else {            printf("FlushFileBuffers -> ret=%d\n", ret);        }        ret = WriteFile(handle, writeBuf, lstrlen(writeBuf)*sizeof(TCHAR), &len, NULL);        if (ret == 0) {            printf("WriteFile buf fail(%ld)\n", GetLastError());        }        else {            printf("WriteFile buf=%ls -> writeLen=%ld\r\n", writeBuf, len);        }        /*        一个文件中设置当前的读取位置        DWORD SetFilePointer(            HANDLE hFile,               // 文件句柄            LONG lDistanceToMove,       // 偏移量(低位)            PLONG lpDistanceToMoveHigh, // 偏移量(高位)            DWORD dwMoveMethod          // 基准位置FILE_BEGIN:文件开始位置 FILE_CURRENT:文件当前位置 FILE_END:文件结束位置        );        return Long，返回一个新位置，它采用从文件起始处开始算起的一个字节偏移量。HFILE_ERROR意味着出错。会设置GetLastError        */        DWORD pos = SetFilePointer(handle, 2, 0, FILE_BEGIN);        if (pos == HFILE_ERROR) {            printf("SetFilePointer fail(%ld)\n", GetLastError());        }        else {            printf("SetFilePointer -> pos=%ld\n", pos);        }        /*        BOOL ReadFile(        HANDLE  hFile,                  //文件的句柄        LPVOID  lpBuffer,               //用于保存读入数据的一个缓冲区        DWORD   nNumberOfBytesToRead,   //要读入的字节数        LPDWORD lpNumberOfBytesRead,    //指向实际读取字节数的指针        LPOVERLAPPED lpOverlapped       //如文件打开时指定了FILE_FLAG_OVERLAPPED，那么必须，用这个参数引用一个特殊的结构。该结构定义了一次异步读取操作。否则，应将这个参数设为NULL        );        return 失败返回0,成功返回非0        注意：ReadFile可以读取文件中所有的数据。如果指针设为FILE_BEGIN的话，有可能读的前几个字节是文件编码，而不是所需的数据，这点要小心        */        ret = ReadFile(handle, readBuf, 1024, &len, NULL);        if (ret == 0) {            printf("ReadFile fail(%ld)\n", GetLastError());        }        else {            //凡是从文件流中读出来的字符串都不会自动补\0，需要手动填充            readBuf[len / sizeof(TCHAR)] = L'\0';            printf("ReadFile -> len=%ld, buf=%ls\n", len, readBuf);        }        CloseHandle(handle);    }    system("pause");    return 0;}