Writing a string to the end of a file (C++)

I have a program already formed that has a string that I want to stream to the end of an existing text file. All of what little I have is this: (C++)

 void main()
{
   std::string str = "I am here";
   fileOUT << str;
}

I realize there is much to be added to this and I do apologize if it seems I am asking people to code for me, but I am completely lost because I have never done this type of programming before.

I have attempted different methods that I have come across the internet, but this is the closest thi开发者_如何学Gong that works and is somewhat familiar.

Open your file using std::ios::app

 #include <fstream>

 std::ofstream out;

 // std::ios::app is the open mode "append" meaning
 // new data will be written to the end of the file.
 out.open("myfile.txt", std::ios::app);

 std::string str = "I am here.";
 out << str;

To append contents to the end of files, simply open a file with ofstream (which stands for out file stream) in app mode (which stands for append).

#include <fstream>
using namespace std;

int main() {
    ofstream fileOUT("filename.txt", ios::app); // open filename.txt in append mode

    fileOUT << "some stuff" << endl; // append "some stuff" to the end of the file

    fileOUT.close(); // close the file
    return 0;
}

Open your stream as append, new text written to it will be written at the end of the file.

I hope that isn't your whole code because if it is, there's lots of things wrong with it.

The way you would write out to a file looks something like this:

#include <fstream>
#include <string>

// main is never void
int main()
{
    std::string message = "Hello world!";

    // std::ios::out gives us an output filestream
    // and std::ios::app appends to the file.
    std::fstream file("myfile.txt", std::ios::out | std::ios::app);
    file << message << std::endl;
    file.close();

    return 0;
}