•
•
•
•
What is DaniWeb IT Discussion Community?
You're currently browsing the C section within the Software Development category of DaniWeb, a massive community of 361,909 software developers, web developers, Internet marketers, and tech gurus who are all enthusiastic about making contacts, networking, and learning from each other. In fact, there are 2,483 IT professionals currently interacting right now! Registration is free, only takes a minute and lets you enjoy all of the interactive features of the site.
Please support our C advertiser:
Views: 2811 | Replies: 1
 |
•
•
Join Date: May 2003
Posts: 1
Reputation: 
Rep Power: 0
Solved Threads: 0
Newbie Poster
i need to be able to add data to my .dat file without deleting my old data during a program run can anyone help me?
•
•
Join Date: May 2003
Posts: 2
Reputation:
Rep Power: 0
Solved Threads: 0
Newbie Poster
•
•
•
•
Originally Posted by gilgamesh
i need to be able to add data to my .dat file without deleting my old data during a program run can anyone help me?
If this is a console app (DOS program) or UNIX program that outputs to standard output, you could redirect the output to your data file
program.exe >> datafile.dat
If this is a Windows program, you can use CreateFile with the following arguments
HANDLE hFile = INVALID_HANDLE_VALUE;
hFile = CreateFile("yourfile.dat",
GENERIC_READ | GENERIC_WRITE,
0, // no file sharing
NULL, // no security descriptor
OPEN_ALWAYS, // creates if not found
FILE_ATTRIBUTE_NORMAL,
NULL); // No template handle
This returns a HANDLE that you can pass to ReadFile and WriteFile
Using SetFilePointer if you need to position to any part of the file.
if (hFile != INVALID_HANDLE_VALUE)
{
DWORD bytesWritten;
if (FALSE == WriteFile(hFile,
dataBuffer, // data to write
dataBufferSize,
&bytesWritten,
NULL)) // not using overlapped I/O
{
MessageBox(GetActiveWindow(),
"Error", "Error", MB_ICONSTOP);
}
// will want to verify
// bytesWritten == dataBufferSize
}
Be sure to close the file with
CloseHandle(hFile);
Hope this helps.
|
•
•
•
•
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
•
•
•
•
•
•
•
•
DaniWeb C Marketplace
Linear Mode
- Please help with data file and array (C++)
- Help creating a data file (C)
- input data from a file into an Array (C)
- Reading from external data file (C++)
Other Threads in the C Forum
- Previous Thread: Question
- Next Thread: Joystick driver
