Make Files

This is a good tutorial on make files link.

If the code is self contained you can run your program with:

gcc prog.c -o prog

If you want to do more complicated stuff the compile command will get much more complicated.

Solution is to use a make utility (or… use CMake :)

# This is a makefile.
CC=gcc
CFLAGS=-Wall
LDFLAGS=-lm
 
myprog: myprog.o more_code.o
	${CC} ${CFLAGS} myprog.o more_code.o ${LDFLAGS} -o myprog
 
clean: 
  \rm myprog.o more_code.o myprog

The make specific variables are in capital letters and they follow a convention such that:

• CC refers to the compiler
• CFLAGS contains compiler directives/options
• LDFLAGS is a list of link (or “load”) directives.
• note there is a tab before ${CC}

The cool thing about make is that it will only compile stuff that has changed since the last time it was ran.

You can have multiple targets in a make file!

The general run down of a make file looks like this:

vars = values
 
target: dependencies
    command-list
 
targ2: more dependencies
    another-command-list

When you run make it opens up Makefile and seeks out the target name if it was specified. If it was not, it runs the first target.

In the end you get a command that says:

Compiler CFLAGS myprog.c LDFLAGS myprog

Ps. Use CMake :)