Where does the eclipse C/C++ generate the executable?

Question

I want to use a relative to open a read file in the C/C++ eclipse, but I would need to know where the eclipse runs the file to put the file in that directory and use the line of code:

ifstream input(".txt file");

instead of:

ifstream input("/home/path/Workspace/program/src/file.txt");

Can someone tell me where the eclipse runs the code?