1. CSCE-221 Makefile Introduction
Emil Thomas
01/17/19
Based on slides by Prof. Jeremy Gibson(UMB) and Prof. Shawn Lupoli (TAMU)

2. Make Overview
make is a program that automates the compilation of programs whose files are dependent on each other
A program typically consists of several files, and a programmer usually only works on a few of them at a time
Typically vast majority of files remain unchanged and thus do not need to be recompiled

3. Why using make and Makefile ?
automated way of compiling
make will only recompile the files that need to be updated (files that depend on modified files), - faster & efficient than recompiling the whole program each time
make looks at the timestamps of source files (*.cpp, *.h) that are required to generate an object file (*.o)
If a source is newer then the object file, the object file needs to be recompiled
Likewise if an object file is newer than the executable it needs to be re-linked
can clean up mess from compiling

4. Compilation process

5. Makefile Structure
A Makefile is a list of rules of what files are required to generate an object or an executable file
Each rule consists of 4 parts:
Target: the name of the object or executable to create
Usually the final executable name and object files
Dependency List: the list of files that the target is dependent upon
For an object file target : the corresponding .cpp file and any user defined “#included” header files in it. (Don’t use system header files)
TAB: used to set off an action
Action(s): a list of actions / linux system commands to take in order to create the target (i.e. g++ …)

6. Makefile Rule foobar.o: foobar.cpp foobar.h
Dependency List
The files that are required to create the object file. In this case foobar.cpp and foobar.h
Target
The file to create. In this case an object file: foobar.o
foobar.o: foobar.cpp foobar.h
g++ -ansi -Wall -c foobar.cpp
<TAB>
Used to signal what follows as an action
Action(s)
What needs to be done to create the target. In this case it is the separate compilation of foobar.cpp

7. Makefile Example & Demonstration
Consider a cpp project with 3 files :
driver.cpp Airplane.cpp Airplane.h
Our objective is to create a Makefile, with the end goal of a executable named “output.out”
Source files setup (look at includes)
Airplane.h
Airplane.cpp
driver.cpp
#ifndef AIRPLANE_H_
#define AIRPLANE_H_
#include <string>
#include <iostream>
using namespace std; …
#include "Airplane.h"

8. Makefile (All the project files should be in the same directory as the Makefile)
output.out: driver.o Airplane.o
g++ -Wall -std=c++11 driver.o Airplane.o -o output.out
driver.o: driver.cpp Airplane.h
g++ -std=c++11 -Wall -c driver.cpp
Airplane.o: Airplane.cpp Airplane.h
g++ -std=c++11 -Wall -c Airplane.cpp
# -f removes any error messages if the file is not present
# *.o mean all files ending with .o
clean:
rm -rf *.o
rm -f *.out

9. Demonstration in compute.cs.tamu.edu
Tabs, not spaces
compiling, running and cleaning the project using Makefile
Selective compiling
Upto date target
Changing timestamp of .cpp .h files (recompiling efficiently using Makefile)
Adding a run target

10. Makefile another Example
Consider a cpp project with files:
main.cpp Point.h Point.cpp
Rectangle.h Rectangle.cpp
Our objective is to create a makefile, with the end goal of a executable named “proj1”
A file/target may depend on one or more other files
Need to ensure correct compilation order

11. Dependency Graph of the files
Point.h
proj1
Point.cpp
Point.o
Rectangle.o
Rectangle.h
Rectangle.cpp
main.cpp
main.o
Link
Include
Compile
Depends on
Source:

12. Makefile proj1: main.o Point.o Rectangle.o
g++ -Wall –std=c++11 -o proj1 main.o Point.o Rectangle.o
main.o: main.cpp Rectangle.h Point.h
g++ -Wall -std=c++11 -c main.cpp
Point.o: Point.cpp Point.h
g++ -Wall -std=c++11 -c Point.cpp
Rectangle.o: Rectangle.cpp Rectangle.h Point.h
g++ -Wall -std=c++11 -c Rectangle.cpp
clean:
rm *.o
rm proj1
run:
./proj1

13. Exercise to be submitted to ecampus
Login to compute.cs.tamu.edu using your netid and password
Putty in Windows
Terminal in mac or Linux
Create a folder csce221 ; and a subfolder lab1_makefile1 and go inside it using the cd command
mkdir csce221
cd csce221
mkdir lab1_makefile1
cd lab1_makefile1
Copy and extract the tar file using
cp /tmp/lecturer.tar .
tar xvf lecturer.tar
Code the cpp and .h files and complete the included Makefile using your favorite editor
See the comments inside the cpp and .h files
Compile and run the code, using the Makefile
By executing “make”
“make run” %You should have a target named ”run” inside your Makefile
“make clean”
Compress the .cpp , .h and Makefile to a single zip file(Don’t include .o or the executable or the original tar file)
Upload the zip file to ecampus under Makefile1

14. Questions ?

15. https://goo.gl/forms/8jQ0296hACw4Lftl2
Complete the survery