I am new to Xcode and am using it in a class to learn c++.

it is difficult for me to create a different project for each new small code we write so I wanted to create only one project and have multiple files under that. I was able to do this by doing to file > new file > c++ file. my first program is called main and it runs fine. the second program on the second file I titled maintwo but this does not run even though it is correct (it runs properly when I paste it into the first main file and delete everything that was there). how can I fix this so that all the new files also run?

thanks