RE: fwrite a hidden file

hi all~
now i try to use "fgets" and "fwrite" to read and modify a file
but if i set the file hidden
i would get error message
"Microsoft Visual Studio C Runtime Library has detected a fatal error in
*.exe"

code:

FILE* file;
char data[512];
CString content[128];
int row=0;

file = fopen("C:\\text.txt", "rt");

while( fgets(data, 512, file) != NULL )
{
    content[row++].Format("%s", data);
}
fclose(file);

if( content[row-1].Find( " /noguiboot /bootlogo" ) != -1 )
{
    content[row-1].Replace(" /noguiboot /bootlogo", "");
    file = fopen("C:\\text.txt", "wt+");
    int line = 0;
    while(line != row)
    {
    fwrite(content[line], sizeof(char), content[line].GetLength(), file);
    line++;
    }
    fclose(file);
}

I don't know what to do to resolve it.
maybe something's wrong..
thanks for help~