Slides I prepared for Deitel and Deitel book titled "C++ How to program"

1. M.Golyani
December 2017
C++ How to program
Mostly based on
Paul Deitel, Harvey Deitel-C++ How to Program-
Pearson (2014)

2. Outline
 History
 Understanding the compiler basics
 What is an executable?
 C++ program structure
 “Hello, World!”
 Input, Output, Error
 Variables and their types
 Getting input from user
 Performing arithmetic operations
 “if” Conditional statement

3. History of programming
 1950s: Fortran, IBM corporation
 1950s: Cobol, Grace Hopper (FLOW-MATIC)
 1960s: Pascal, Niklaus Wirth
 1960s: Basic, Dartmouth College
 1970s: Ada, DoD
 1972: C, Dennis Ritchie
 1979: C++, Bjarne Stroustrup
 1991: Java, Sun Microsystems
 2001: C#, Microsoft
 , …

6. Programs
- A sequence of instructions which perform
a specific task
- The CPU is responsible for executing the commands.
- Each instruction is finally executed by the CPU.
- The final program should be understandable for the CPU
- CPU does not understand the ASCII, human readable texts (known
as source files!!)
- We should translate these sources to machine codes.
- No matter what programming language we use, the CPU instruction
set is fixed.

7. Programmers

8. Programmers

9. Programmers

10. Programmers
http://Stuffthathappens.com
Eric burke

11. Compiling the Source
- Compiling a source file to create an executable, is performed in
some steps as bellow:
Preprocessing
Compiling
Assembling
Linking
Compiler does these in
one or more passes

12. Compiling the Source
- Compiler does some analysis on source file:
Lexical
Syntax
Semantic
Optimizing the Code
Code Generation
Symbol Table
Error Handler
Intermediate Code Generation

13. Linux C++ compiler
 g++:
 g++ <SOURCE>
 g++ -o <EXECUTABLE> <SOURCE>
 gcc:
 gcc <SOURCE>
 gcc -o <EXECUTABLE> <SOURCE>
 GCC: GNU Compiler Collection

14. Linux C++ compiler
- The Gnu Compiler Collection (GCC) project started by Richard
Stallman in 1985.
- GCC includes front-ends for lots of languages including:
• C (gcc)
• C++ (g++)
• Java (gcj)
• Ada (GNAT)
• Objective-C (gobjc)
• Objective-C++
• Fortran

16. Linux Executables
ELF
Relocatable File (.o files)
Shared Object File (.so files)
Executable File
There are 3 main ELF object files:
Linux executable files are in ELF format (Executable and Linkable
Format)
There is no need for specific file extension in Linux, only permission
Core Dumps

17. C++ libraries
 Each C++ program consists of “classes” and
“functions”
 These are pieces of code that perform special tasks
 Printing a string in the output, opening a file for
writing, accessing specific parts of the memory and
…
 If your program needs to do these tasks, you can
write the code yourself, or you can use the already
provided functions and classes.
 These already prepared functions and classes are
packed into “libraries”
 There are lots of libraries available and you can

18. C++ libraries
 Shorter development time
 Probably better performance
 Improves program portability
 You don’t need to worry about updating and
maintenance of these libs.
The “C++ standard library” is a rich collection of most
needed functions and classes

19. C++ header files
 The C++ standard library is automatically attached to
your program.
 The functions and classes in the C++ standard library
are categorized into several sections.
 To use each section, you should “include” the
appropriate header file in your source code.
 To include a header file, you should use “#include”
phrase. #include <iostream>

20. C++ header files
Header file Usage
iostream
Several standard stream objects
(input, output, …)
memory Memory management utilities
cerrno To view the last error number
cmath Common mathematics functions
chrono C++ time utilities
… …
… …

21. How can we make our
own header files ???

22. Sample C++ program structure
#include
<iostream>
int main()
{
….
/*
These lines
are comment
as well
*/
….
return 0;
}
// This is a comment
Header files that we need
Compiler will not compile this
line
This means
that the main()
function is
going to return
an integer
after it finishes
it’s work
Each program
should have a
“main” function
This return value is used by
other programs and shell to
check for errors.
There could be lots of other
functions and codes in our
program, starting from main
function

23. Hello, World!
You need to know how to create a text file
in Linux CLI
This entity belongs
to “std” namespace
We indicate that this
way
Returning a Zero from main
means that the program
has ended successfully
Lines starting with # are
directives to the “preprocessor”
which is run before the compiler.
This line tells the preprocessor to
include the “iostream” header file

24. Hello, World!
 Always use and update comments in your code
 C++ statements should end with “;” (almost all of
them)
 “syntax error” indicates you have something wrong in
your coding syntax.
 Whitespaces and blank lines are OK.
 Use “TAB”, blank lines and whitespaces to have a
human readable code!

25. Input, Output, Error
 The std namespace contains some “standard”
library routines.
 cin:
 Used to get data from standard input
 cout:
 Used to send data to standard output
 cerr:
 Used to send data to standard error
 , …
Usually the STDIN, STDOUT, and STDERR are
connected to the working terminal

26. Input, Output, Error
Use “std::cerr” to send error messages to STDERR

27. How can we redirect
program’s output to one
file and errors to
another?

28. Escape sequence
 The “” character in output string is an “escape
character”
 According to what comes after “”, the output
differs.
 The “” and the following character is named
“escape sequence”

29. Variables
 We use variables to store data.
 Variables are placed in computer’s memory
(RAM).
 To use a variable, we should first declare it.
Variable
declaration
Add comments here
to remember why
you have declared
this variable
Variable declaration could be anywhere, just
remember to declare before use

30. Variables
 Each variable has its own type, name, size, and
value.
 Integer, float, double,…
 String, char, …
 , ….
The “int” phrase is a
keyword. We can’t use
keywords as our variable
names!

31. C++ variable types
Type Meaning Example
int Integer numbers -3, 0, 5
double Real numbers 3.4, 0.04, -2.5
float Real numbers ???
char Any single character ‘A’, ‘+’, ‘*’
bool Boolean type “true” or “false”
… … …
Type Meaning
Signed Negative or positive
Unsigned Only positive
Long At least 32 bits
Short At least 16 bits

32. Input from user
 Using std::cin, you can get input from command
line.
 Remember the direction of “>>” and “<<“
 Using “std::cout” at each statement is awkward!

33. How can we provide a
program’s required
inputs to avoid
interaction?

34. Arithmetic operations
 You can use “using” declaration to avoid
repeating “std::”

35. Arithmetic operations
 The precedence of arithmetic operations are
important.
 Parentheses are always considered first.

36. y = a * x * x + b * x + c ;
Arithmetic operations
16 2 4 3 5

37. Arithmetic operations
 What is the output of this program?
 1  2  9  10  0

38. Arithmetic operation
If there are lots of names
that we want to use, we
should declare them here

39. Conditional statement
 “if” statement is used to implement conditional
statements.
if ( CONDITION )
{
.......
.......
.......
}
else
{
.......
.......
.......
}
If “CONDITION” is true,
then this piece of code is
executed
If “CONDITION” is NOT
true, then this piece of code
is executed

40. Conditional statement
 “CONDITION”s in if statements, can be formed by
using the “relational operators” and “equality
operators”

41. Conditional statement
 What is wrong in this program?
Notice that we used “using”
directive here instead of
using multiple using
declaration.
This enables the program
to use all the names in any
standard C++ header that
a program might include.
If the statements of the
condition are one line
length, you can omit the {
… } block.

42. End of Section 1
 In this section, you learned about:
 What is an executable
 How compilers work
 What are libraries and headers
 C++ program structure
 How to send strings to stdout, stderr
 How to get user input from stdin
 Variables and their types
 Arithmetic operations and their precedence
 “if” conditional statement and it’s usage