Increasing Optimization Level g++
c++, cygwin, g++, optimization
Solution
That should be `-O3`, not `-o3`. Otherwise you're telling g++ to put the compiled executable into a file named `3`, and you're feeding it `main`, your previously-compiled executable, as input. It's probably trying to interpret that as source code, hence the errors.
Problem
I'm trying to compile a relatively simple c++ program using cygwin and g++. I can compile it using the following command: `g++ -o main main.cpp -lgmpxx -lgmp` (note: the last two reflect the inclusion of the gmp libraries). I'd like to increase the level of optimization that this is compiled with. I thought that I could just change this command line to: `g++ -o3 main main.cpp -lgmpxx -lgmp` but this totally blows up. I get about two full screens of error messages. How can I increase the optimization here? Thanks!