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MFC
Example: CFile and Creating a
File, Open, Write, CFile::modeCreate, CFile::
modeReadWrite
CFile
is the class used for handling Files in MFC. This class
can be used for creating,
reading, writing and
modifying
files. It directly provides unbuffered, binary disk
input/output services, and it indirectly supports text
files and memory files through its
derived classes.
CFile -
Creating a File:
There are two ways of
creating files. One way is to instantiate the CFile object
with the file
path. This creates the
file. The second
way is to call the Open function. This also creates the
file.
CFile
cfile_object( "c:\\test\\ ucancode_cfile_example.txt",
CFile::modeCreate|CFile:: modeReadWrite);
CFile cfile_object;
cfile_object.Open( "c:\\test\\ucancode_cfile_example.txt",
CFile::modeCreate|CFile::
modeReadWrite);
The
first parameter to both the functions (CFile() constructor
and Open()) is the physical path of the file in the disk. The
second parameter is an enumerated constant. This specifies
the mode of opening the file object. The above constants modeCreate
implies "create a new file" and
modeReadWrite
means "open the file for both reading and
writing".
If the file is opened without specifying the mode constant
shareDenyNone, this file can be opened in read mode
by other programs. This feature will be necessary for
text files, logs created by programs. For creating text
files we use CFile::typeText and for binary files
CFile::typeBinary.
CFile -
Writing to a File:
The function Write is used to
write data to the files. The sample code is as follows.
CFile cfile_object;
cfile_object.Open(
"c:\\test\\ ucancode_cfile_example.txt",
CFile::modeCreate|CFile::modeWrite);
char szSampleText[100];
strcpy(szSampleText, "Sample
Text for CFile Write function Example");
cfile_object.Write
(szSampleText,100);
If there is any need to write
text line by line, it is better to use the class
CStdioFile.
CFile -
Reading from a file:
The function Read is used to
read data from files. The sample code is,
CFile cfile_object;
cfile_object.Open(
"c:\\test\\ ucancode_cfile_example.txt",
CFile::modeCreate|CFile::modeWrite);
char szSampleText[100];
UINT lBytesRead =
cfile_object.Read (szSampleText,100);
The function
returns the number of bytes read from the
file. The maximum number of characters read will be the
second parameter of the Read function.
CFile -
closing the file:
The Close function is used to
close the file. But the close function need not be called,
as the destructor will automatically call it if the
file is open. So when the object goes out of scope, the
destructor calls close function.
Full
VC++ Source Codes, Tutorial
and Example
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