Thread: How to insert data to the top of exist text file?

I want to insert "{" to the top of exist text file and insert "}" to the bottom of text file

Example:

If in "1.txt" has this data in it.

1234afd
daf845
dfdfa

and I want to insert "{" to the top of text file and insert "}" to the bottom of text file. So I think it should be like this

{
1234afd
daf845
dfdfa
}

I write program to do that. But my program replace "{" to the first line data of "1.txt"

So my program write this data in "1.txt"

{
daf845
dfdfa
}

Below is my program.

Code:

CStdioFile OutputFile;
CString outp_filename, m_string; 
CFileException FileExc;
BOOL bEnd;

	outp_filename = "1.txt";

if (!OutputFile.Open(outp_filename, CFile::modeCreate | CFile::modeWrite | CFile::modeNoTruncate, &FileExc)) 
{
FileExc.ReportError();
return;
}
OutputFile.SeekToBegin();

m_string = "{";

OutputFile.WriteString(m_string+'\n'); 

OutputFile.SeekToEnd();

m_string = "}";

OutputFile.WriteString(m_string+'\n');

OutputFile.Close();

}

Do you know how to solve my problem?
Thank you very much.

There are several solutions.

One experient is to append data at the beginning and end of the file using write(). Make sure you open the file with the append flag (ios::app). Another solution is to map the file's contents into virtual memory using file-mapping. That will allow you to modify its contents at any given point.

Kuphryn

You can try the following method it works

First read the first string and store it
append it to the end of the string you want to insert at top
Insert the combined string at top

this new string will replace the old first string at the top of the file but anyway the inserted new string contains the old string in it

Code:

void CMyClass::AddTextAt TheTopOf TheFile(LPCTSTR szFile, LPCTSTR szText)
{
	if ((szText == NULL) || (szText == "")) return ;
	CString str;


	char s[81];
	CFile file;   
  
	if (!file.Open(szFile, CFile::modeRead)) return ;
	file.SeekToBegin();
	int bytesRead = file.Read(s, 80);
                s[bytesRead] = 0;
                CString message = s;
	file.Close();

	if (!file.Open(szFile, CFile::modeWrite)) return ;
	file.SeekToBegin();
	str.Format("%s\n%s\n",szText,message);
	file.Write(str,str.GetLength());
	file.Close();

}

Only problem is you have to open the file twice once in Read mode once in Write mode. hope this helps
Thanks