How to write the result of a function to a file C++

Question

I think this is a pretty simple question, but I didn't find the answer.

I wish to write the result of a function to a file.

The file is open, and I'm able to write a simple string to it, but not the result of the function.

What I am missing?

#include <iostream>
#include <fstream>
using namespace std;

void addingtext(){
    for (int i = 0; i < 8; ++i)
    {
        std::cout << i << endl;
    }
}

int main () {
    ofstream file;
    file.open("example.txt");
    if(file.is_open()){
        std::cout << "File Open Access \n";
    }
    file << "Write this to the file";
    addingtext();
    //file << addingtext;

    file.close();

    return 0;
}

Answer 1

addingtext() returns nothing, and writes to std::cout .

You have two options:

Option 1: Make addingtext() return a string, and then write that to the file:

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

std::string addingtext() {
    std::string result;
    for (int i = 0; i < 8; ++i)
    {
        std::cout << i << endl;
        result += i;
        result += "\n";
    }
    return result;
}

int main() {
    ofstream file;
    file.open("example.txt");
    if (file.is_open()) {
        std::cout << "File Open Access \n";
    }
    file << "Write this to the file";
    file << addingtext();

    file.close();

    return 0;
}

Option 2: Make addingtext() write to the file:

#include <iostream>
#include <fstream>
using namespace std;

void addingtext(ofstream& o) {
    for (int i = 0; i < 8; ++i)
    {
        std::cout << i << endl;
        o << i << endl;
    }
}

int main() {
    ofstream file;
    file.open("example.txt");
    if (file.is_open()) {
        std::cout << "File Open Access \n";
    }
    file << "Write this to the file";
    addingtext(file);

    file.close();

    return 0;
}

Answer 2

Your function does not return any value.

If it returned a value, such as a string you have created during the running of the addingtext function you could then add that string straight to the file as you are doing there.

Answer 3

I think you want to pass the file stream to your function so it writes to the file instead of std out.

void addingtext(ofstream& stream){
    for (int i = 0; i < 8; ++i)
    {
        stream << i << endl;
    }
}

int main () {
    ofstream file;
    file.open("example.txt");
    if(file.is_open()){
        std::cout << "File Open Access \n";
    }
    file << "Write this to the file";
    addingtext(file);
    //file << addingtext;

    file.close();

    return 0;
}

Answer 4

If you want your function to return a string, don't declare it's return type as void. I would:

#include <string>

string addingtext(){
    string temp;
    for (int i = 0; i < 8; ++i)
    {
        temp += i;
    }
    return temp;
}