introduction to c++ lecture 1 - suleyman demirel...

Instructor: Bakhyt Bakiyev

Basic things

content

Introduction: history of C and C++, and differences.

Data types

if, if – else, conditional operators,

switch

loops

C is a general-purpose computer programming

language developed in 1972 by Dennis Ritchie at the Bell

Telephone Laboratories for use with the Unix operating

system.

C++ was written by Bjarne Stroustrup at Bell Labs

during 1979-1985. C++ is an extension of C. Bjarne

Stroustrup added features to C and he called it as "C with

Classes". An then the term C++ was first used in 1983.

History of C and C++

http://www.cs.bell-labs.com/who/dmr/

http://www2.research.att.com/~bs/homepage.html

C and C++ difference

C++ is a general–purpose programming language with a bias

towards systems programming

is an extension of C;

supports data abstraction

supports object-oriented programming

First program in C++

#include<iostream>

using namespace std;

int main()

{

cout<<”salem SDU! \n”;

return 0;

}

salem SDU!

// first program in C++

This is a comment line. All lines beginning with two slash signs

(//) are considered comments and do not have any effect on the

behavior of the program. The programmer can use them to

include short explanations.

#include <iostream>

Lines beginning with a hash sign (#) are directives for the

preprocessor. #include <iostream> tells the preprocessor to

include the iostream standard file. This specific file (iostream)

and includes the declarations of the basic standard input-output

library in C++.

main ()

This line corresponds to the beginning of the definition of the

main function. The main function is the point by where all C++

programs start their execution, independently of its location

within the source code. It does not matter whether there are

other functions with other names defined before or after it - the

instructions contained within this function's definition will

always be the first ones to be executed in any C++ program.

Escape Sequence

\n - Newline. Position the screen cursor to the beginning of the

next line.

\t - Horizontal tab. Move the screen cursor to the next tab stop.

\r - Carriage return. Position the screen cursor to the beginning

of the current line.

#include<iostream>

using namespace std;

int main()

{

// first program in C++

cout<<”Salem \n”<<“SDU !”;

return 0;

}

Salem

SDU!

Memory concepts a = 5;

b = 2;

a = a + 1;

result = a - b;

Any variable names actually correspond to locations in the

computer's memory. Every variable has a name, a type, a size and

a value.

Notice, we can give any names for variables except reserved

words.

The standard reserved keywords:

asm, auto, bool, break, case, catch, char, class, const, const_cast,

continue, default, delete, do, double, dynamic_cast, else, enum,

explicit, export, extern, false, float, for, friend, goto,if, inline,

int, long, mutable, namespace, new, operator, private, protected,

public, register,reinterpret_cast, return, short, signed, sizeof,

static, static_cast, struct, switch, template, this, throw, true, try,

typedef, typeid, typename, union, unsigned, using, virtual, void,

volatile, wchar_t, while.

Fundamental data types Name Description Size Range

char Character. 1byte signed: -128 to 127 unsigned: 0 to 255

short int (short)

Short Integer. 2bytes signed: -32768 to 32767 unsigned: 0 to 65535

int Integer. 4bytes signed: -2147483648 to 2147483647 unsigned: 0 to 4294967295

long int (long)

Long integer. 4bytes signed: -2147483648 to 2147483647 unsigned: 0 to 4294967295

bool Boolean value. It can take one of two values: true or false.

1byte true or false

float Floating point number. 4bytes (~7 digits)

double Double precision floating point number.

8bytes (~15 digits)

long double Long double precision floating point number.

8bytes (~15 digits)

wchar_t Wide character. 2 or 4 bytes

1 wide character

Scope of Variable A variable can be either of global or local scope.

Taking an information For example:

int age;

cin >> age;

There is also usage of cin to request more than one data from the

user:

cin >> a >> b;

is equivalent to:

cin >> a;

cin >> b;

Displaying an information For example:

int age=20;

cout <<age;

There is also usage of cout to display more than one data at a time:

int a=10, b=20;

cout << a << b;

is equivalent to:

cout << a;

cout<<b;

Assignment (=) The assignment operator assigns a value to a variable.

a = 5;

a = 2 + (b = 5);

is equivalent to: b = 5; a = 2 + b;

Arithmetic operators

C++ operation

C++ arithmetic

operator

Algebraic

expression

C++

expression

Addition + x + y x + y

Subtraction - x - y x – y

Multiplication * xy or x · y x * y

Division / x/ y

Modulus % x mod y x % y

if & if-else

Nested if-else

if ( x > 5 )

if ( y > 5 ) cout << "x and y are > 5";

else cout << "x is <= 5";

if ( x > 5 )

{

if ( y > 5 ) cout << "x and y are > 5";

}

else cout << "x is <= 5";

(= and ==)?

Bool data type Bool data types can take only 2 values true or false, false is equal to 0 and true is equa

l to 1.

Char data type In C++ char data type is used for a single character. Collection of char

acters is ASCII.

Note: char c='a' works fine, but char c=“a”; is compilation error.

Scope A variable can be either of global or local scope. If there is same name for global and l

ocal variable “::” keyword is used for global.

Escape codes

In C++ there are escape codes, which are used to express more additional symbols

or actions. Its structure consists of “\” sign and letter.

Type casting There are 2 ways:

answer = (double) (numerator) / denominator

answer = static_cast<double>(numerator) / denominator

Conditional operator ? In C++ it can be used conditional operator “?” instead of if .. else structure.

Its structure is : condition ? result1 : result2;

Short writing operators For example “x = x + 5;” can be written as “x += 5;”

Also for short writing code increase (++) or decrease (--) are used.

pre – post

Comparision

relational operator meaning_________

> x is greater than y

< x is less than y

>= x is greater than or equal to y

<= x is less than or equal to y

== x is equal to y

!= x is not equal to y

Logical operators

3 main logical operators in C++: “and” (&&), “or” (||) and “not” (!).

Math library

switch switch ( integer expression )

{

case constant 1 :

do this ;

case constant 2 :

do this ;

case constant 3 :

do this ;

default :

do this ;

}

Ex: main( )

{

int i = 2 ;

switch ( i )

{

case 1 : cout<<"I am in case 1 \n" ; break ;

case 2 : cout<<"I am in case 2 \n" ; break ;

case 3 : cout<<"I am in case 3 \n" ; break ;

default : cout<<"I am in default \n";

}

}

LOOPs

while

do … while

for

WHILE The “while” loop's structure is : while (condition(s) is(are) true) { code }

In while loop there must be increment (decrement) operations or some checking to make condition false, otherwise it can infinite loop.

DO … WHILE

The “do .. while” loop's structure is do { code } while (condition[s] is[are] true); The main difference between do/while and while loops is that sometimes in do/while it can be 1 mo

re step, because firstly it run code then checks the condition.

FOR

The “for” loop's structure is: for (initialization; condition; increase)

STRUCTURE

FOR vs WHILE

BREAK

Break command is used to finish loop and exit from loop even if the loop condition is true.

CONTINUE The continue causes to pass rest of loop and go to next iteration.

EXIT

The “exit” is used to terminate program even if it is not finished. It can be used when error happens in code.

while (true) {

}

INFINITE LOOPS

Statements with “for”

for (i=0, j=1; i<=10; i=i+2, j++) {

j = j+3; i++;

}

FOR in sdutents’ dining-hall

FOR (SDUdent i = 1; i<=7; i++)