C++: Write to an existing file?

Question

In C++, I need to write to an existing file and keep the previous content there.

This is what I have done:

std::ofstream logging;

logging.open(FILENAME);

logging << "HELLO\n";

logging.close();

but then my previous text is overwritten (gone). What did I do wrong?

Thanks in advance.

Answer 1

logging.open(FILENAME, std::ios_base::app); 

Answer 2

You have to open the file in append mode:

logging.open(FILENAME, std::ios::app);

Answer 3

By default the "opening mode" for a file is overwrite. Try opening the file in append mode

The second parameter of open is an enum bitflag. The two options you should check out are:

• app - seek to the file end before each write

• ate - seek to the file end after open

  logging.open(FILENAME, std::ios::app|std::ate);

Answer 4

do you try ? something like that

myFile.open( "file.txt", ios::out | ios::app );