What does -Wall flag do when I compile it with the program?

Question

I am following a tutorial that says how to profile the program using gprof and the command given is like this

gcc -Wall -pg test_gprof.c test_gprof_new.c -o test_gprof

But it doesn'y give any explanation for this flag (-Wall)

Answer 1

As the name suggests it tells the compiler to enable all warning messages i.e. unused variables. This would help you to write better and clean code.