文件操作（判断状态、删除、新建、复制、清空文件内容、获取文件长度）

判断状态
#include<io.h>
int _access( constchar*path,intmode);
返回值: 0表示允许访问，-1表示禁止访问


CreateFile
 
HANDLE hFile=CreateFile("c://123.bmp",GENERIC_WRITE|GENERIC_READ,
OPEN_EXISTING, //OPEN_EXISTING 
               FILE_ATTRIBUTE_NORMAL,NULL);
  if(hFile==INVALID_HANDLE_VALUE)//标示文件不存在

删除

BOOL DeleteFile(LPCSTR szFileName);
int SHFileOperation(LPSHFILEOPSTRUCT);

新建

WINBASEAPI
HANDLE
WINAPI
CreateFileW(
    LPCWSTR lpFileName,
    DWORD dwDesiredAccess,
    DWORD dwShareMode,
    LPSECURITY_ATTRIBUTES lpSecurityAttributes,
    DWORD dwCreationDisposition,
    DWORD dwFlagsAndAttributes,
    HANDLE hTemplateFile
    );
   CreateFile("123.txt", GENERIC_WRITE|GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
 
  #include <stdio.h>
  fopen("123.txt","wb+");

复制

CopyFile
SHFileOperation
 
清空文件内容
SetFilePointer(hFile,0,NULL,FILE_BEGIN);
 
SetEndOfFile(hFile);
 
 
HANDLE hFile=CreateFile("c://123.bmp",GENERIC_WRITE|GENERIC_READ,
,TRUNCATE_EXISTING,//已清空文件的方式打开
               FILE_ATTRIBUTE_NORMAL,NULL);

获取文件长度

1、

#include <stdio.h>
 
FILE *fp=fopen("c:/123.bmp",rb);
fseek(fp,0,SEEK_END);//文件指针移到尾
ulong flen=ftell(fp);//文件长度
fseek(fp,0,SEEK_SET);//移回来

2、

#include <stdio.h>
     #include <io.h>
    FILE *fp=fopen("c:/123.bmp",rb);
    ulong flen=filelength(fileno(fp));

3、

#include <sys/stat.h>
    struct _stat info;


           _stat(filepath, &info);
     int size = info.st_size;

4、

HANDLE hFile=CreateFile("c://123.bmp",GENERIC_WRITE|GENERIC_READ,      


,OPEN_EXISTING,
               FILE_ATTRIBUTE_NORMAL,NULL);


           DWORD dwflen=GetFileSize(hFile,NULL);      


           CloseHandle(hFile);

mode value

00

检测是否存在

02

写权限

04

读权限

06

读写权限