Headerfiles and Makefiles

Question 1

What are Header (.h) files?

Answer 1

Templates / short snippets of code to be implemented in a .cpp file.

Question 2

Headerfiles and MakeFiles

How are header files added?

Answer 2

#include “header_file.h”
(“ “, not < >)

Question 3

What does including a .h file accomplish in a .cpp file?

Answer 3

It essentially copies the .h file to the top of the .cpp file.

Question 4

Headerfiles and MakeFiles

As a rule of thumb, what should header files contain?

Answer 4

• Include Guards
• Definitions and outline for code.
• Some small simple code, ex getters and setters.

Question 5

Headerfiles and MakeFiles

Should “using namespace” be used in header files?

Answer 5

No, because it will add the code in the .h file to the namespace, rather than add the namespace to the global namespace like in .cpp files.

Question 6

Headerfiles and MakeFiles

How do you access/implement a free floating function from a .h file?

Answer 6

Directly using the same footprint as defined in the .h file.

Question 7

Given class method DoStuff(int i); in class MyClass declared in a .h, how would you implement this in a .cpp?

Answer 7

With a reference to the class name. (i.e: MyClass::DoStuff(int i) {…}) or with “using namespace MyClass” At the top of the .cpp.

Question 8

What are include guards?

Answer 8

A pre-compiler command to tell the compiler not to duplicate .h code if already included.

Question 9

What is the syntax of include guards?

Answer 9

#ifndef FILENAME_H

#define FILENAME_H

…some code…

#endif FILENAME_H

Question 10

What is a .o file?

Answer 10

A file that contains the machine code representation of your code, but not yet executable.

Question 11

What is a .a file?

Answer 11

An archive file that contains a library of compiled .o files.

Question 12

What is the relation between a archive and header files?

Answer 12

The .h file acts as a translator between the user and the .a file.

Question 13

What is a Makefile

Answer 13

A text file containing a list of commands

Question 14

What are targets in a Makefile?

Answer 14

Names of Makefile Commands.

Question 15

What whitespace does a Makefile use?

Answer 15

Tabs, not spaces.

Question 16

What is the default command in a Makefile?

Answer 16

The first command in a Makefile, or the commands under the ‘all’ target.

Question 17

What is a dependency in a Makefile?

Answer 17

A list of commands before the Make target can run.

Question 18

What is the syntax of a Makefile dependency?

Answer 18

target : dependencies
ex:
HelloWorld : hello.o

Question 19

If a dependency is not found as a target in a Makefile, what happens?

Answer 19

It searches for a file by the same name.

Question 20

What is a Makefile ‘Pattern’?

Answer 20

A target that uses a pattern rule to streamline a command.

Question 21

How is a Makefile pattern rule made syntactically?

Answer 21

With %. For example, %.o will look for any make command with a .o, and replace % with that command.

Question 22

What does the following code do in a Makefile?
%.o : %.c
g++ –g –Wall –c $<

Answer 22

Looks for any make command with .o, searches for the requisite.c, and uses that .c where the $< is.

Question 23

In a Makefile pattern, what does $< represent?

Answer 23

Any dependency file for a given target.

Question 24

In a Makefile, what is the ‘.PHONY:’ command?

Answer 24

It tells Makefile not to expect a file to be created.

Question 25

What are the 3 compilation flags required for this course?

Answer 25

• Wall
• Wfatal-errors
• Werror

Question 26

What is the ‘Wall’ complation flag?

Answer 26

All of the basic warnings for unstable code.

Question 27

What is the ‘Wfatal-errors’ complation flag?

Answer 27

Any error stops compilation.

Question 28

What is the ‘Werrors’ complation flag?

Answer 28

Compiler will treat all warnings as errors.