Using the GNU Compilers on the CS Linux Machines

Current configurations for our classroom/lab machines include multiple versions of the GNU compilers:

• The most recent version available from the standard repositories for the distribution we use. This is the version you get by default. (gcc --version will tell you what it is.)
• One or more later versions obtained directly from the GNU project's Web site, installed in /usr/local-gcc-*-install. During the annual summer upgrade we install the most recent stable version available and may install some earlier versions as well. The simplest way to access the most recent version of these compilers from the command line is to use the command

  module load gcc-latest

  to add the install directory to your command search path and set other environment variables correctly. If you want this to happen every time you log in, you can add the above command to your .bashrc file. See my notes on the “Modules package” for more about modules.

Using make

I strongly encourage students in my classes to always compile C programs with at least the optional flag -Wall, and preferably several additional flags. No sensible person would type them all for every compile, but make can help. Create a file Makefile consisting of the single line

CFLAGS=-std=c99 -Wall -pedantic -O

(or whatever options you prefer -- note that the last one is a capital O). Then for example compile foo.c with

make foo

(The resulting executable will be called foo rather than the default a.out.)

If you're compiling C++ instead (or in addition), add this line to the Makefile:

CXXFLAGS=-std=c++98 -Wall -pedantic -O

(or whatever options you prefer -- if you're using the latest version of g++ you may want to replace -std=c++98 with -std=c++17). Then compile foo++.cpp with

make foo++