Question

Please correct the below code:only.

file already contains entries : 1st row username; 2nd row password.

checkbox status required to write to the third line and need to read or alter only the checkbox status value in the file.

Currently this code is working if there already is a value for the checkbox status value, then it is overwriting, else UI is hanging.

WriteCheckStatusToFile(BOOL& locVar)
{
    FILE *l_pFile = NULL;
    CString l_strRememberCheck;
    l_strRememberCheck = GetExePath() + _T("password");

    CString sVar;
    sVar.Format(_T("%d"),locVar);
    if(NULL != (l_pFile = fopen(l_strRememberCheck, _T("r+"))) )
    {
        int count = 0;
        char c;
        while(count != 2)
        {
            if((c = fgetc(l_pFile)) == '\n') count++;
        }
        fseek(l_pFile,ftell(l_pFile),SEEK_SET);
        fprintf(l_pFile, sVar);
    }
    l_strRememberCheck.ReleaseBuffer();
    fclose(l_pFile);
}

thanks in advance to all!
sam.

Answer 1

This line

fprintf(l_pFile, sVar);

doesn’t look right. I think it should be

fprintf(l_pFile, "%s\n", (LPCTSTR) sVar);

The loop could become infinite if the file has less than two linefeeds:

while(count != 2)

I think it should be:

while( (count < 2) && ( ! feof(l_pFile) ) && ( c != EOF ) )

Probably unrelated to your error, but – at least for this code snippet – CString::ReleaseBuffer() doesn’t need to be called since you have not called CString::GetBuffer().

l_strRememberCheck.ReleaseBuffer();

This line may be unnecessary as it appears to fseek() to where the file pointer already is:

fseek(l_pFile,ftell(l_pFile),SEEK_SET);

In the event a two-line file is not terminated with a ‘\n’ you would need to print like this:

   if ( count == 2 )
   {
      fprintf(l_pFile, "%s\n", (LPCTSTR) sVar);
   }
   else
   {
      fprintf(l_pFile, "\n%s\n", (LPCTSTR) sVar);
   }