"Go" MFC Read and write files with CFile 2

Original URL: http://blog.sina.com.cn/s/blog_623a7fa40100hh1u.html

CFile provides some common operating functions, as shown in table 1-2.

Table 1-2 CFile operator Functions
Function	Meaning
Open	Open File
Close	Close File
Flush	Refresh the data to be written
Read	Reading data from the current location
Write	Write data to the current location
GetLength	Get the size of a file
Seek	Position the file pointer to the specified location
Seektobegin	Position file pointer to file header
Seektoend	Locate the file pointer to the end of the file
GetFileName	Gets the file name, such as:"NOTEPAD. EXE "
GetFilePath	Gets the file path, such as:"C:\WINDOWS \notepad. EXE "
GetFileTitle	Get the file title, such as:"NOTEPAD"
GetPosition	Gets the current file pointer
GetStatus	Gets the status of the current file, returning a cfilestatus
#Remove	static method, delete the specified file
#Rename	static method, renaming the specified file

Note that the last two static functions, in fact, encapsulate the functions of the Windows API for file management.

the process for manipulating files using CFile is as follows:

Constructs a CFile object.

Call the CFile::Open () function to create and open the specified file.

Call Cfile::read () and cfile::write () for file operations.

Call CFile::Close () to close the file handle.

The location settings for the file pointer can be used:

Seek ( LONG loff, UINT nfrom ) Move the file pointer to the specified position

Loff : Is the pointer offset byte number, or positive if the backward offset, or negative if the forward offset.

Nfrom : There are three types of values on MSDN:

Cfile::begin starting from the beginning of the file,Loff is a positive number;

Cfile::current the current position begins;

Cfile::end starting from the end of the file, theloff is negative;

Seektobegin ( ) Move the file pointer to the beginning of the file

seektoend ( ) Move the file pointer to the end of the file

GetPosition () Returns the position of the current file pointer

Gets the number of bytes of the file available getlength ( ) The return value of this function is DWORD, but it can be used directly to allocate the number of array elements, for example:

DOWRD Len=file. GetLength ();

Char *pbuf=new char[len+1]/int *pbuf=new INT[LEN/4]

Char occupies one byte, andint accounts for four bytes.

Write file:

CFile file;

File. Open ("E:\\vc\\1.txt", cfile::modecreate| cfile::modewrite| Cfile::modenotruncate,null);

File. Write ("HelloWorld", strlen ("HelloWorld"));

Write ( const void* lpbuf, UINT ncount ) lpbuf is the Buf pointer that writes the data ,ncount is the number of bytes in the Buf that need to be written to the file

File.close ();

Read file:

CFile file;

File. Open ("E:\\vc\\1.txt", cfile::moderead,null);

DWORD Len=file. GetLength ();

Char buf[len+1];

buf[len]=0; 0 terminating string for output.

File.   Read (Buf,len); Read ( void* lpbuf, UINT ncount ) lpbuf Is the Buf pointer that is used to receive the read data ncount is the number of bytes read from the file

MessageBox (BUF);

"Go" MFC Read and write files with CFile 2