Computer Engineering 1st Semester

Dr. Rabie A. Ramadan

http://rabieramadan.org

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C++ Names

The name of a variable could: • Starts with an underscore “_” or a letter, lowercase or uppercase, e.g.

_Students, pRice

• Can include letters, underscore, or digits. Examples are: keyboard, total_grade, _Score_Side1

• Cannot include special characters such as !, %, ], or $

• Cannot include an empty space

• Cannot be any of the reserved words

• Should not be longer than 32 characters (although allowed)

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Reserved Words

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Variables and Their Data Types

The amount of memory space necessary to store a variable is also referred to as a data type.

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Variables and Their Data Types

char 8 bits

Signed char:• -128 +127

Unsigned char • 0 255

Escape sequences are characters

Escape characters

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Examples

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Variables and Their Data Types Integers – 32 bits or 4 bytes

• Holds numerical data

• Signed or Unsigned

Short integers • 16 bits or 2 bytes

• Signed or Unsigned

Long integers• To enforce positive numbers

• 32 bit long

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Example

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Practice -- what is the o/p

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Practice -- what is the o/p

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O/P

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Variables and Their Data Types

Floating points

• Real numbers ex. 5.5

• 4 bytes

• Declared as : float x;

Floating number with double precision

• 8 bytes

• Declared as : double x;

Larger storage

• 10 bytes

• Declared as: long double x;

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Example

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Variables and Their Data Types

String

• Group of characters

• No limit

• Declared as: string name;

getline() function

• Takes the data from external source and save it into a string variable

• Ex. getline(cin, name);

• cin is to notify the compiler that the data is coming from external source

• Ex. getline( cin, name, ‘?’) getline( cin, stringName, delimiter )

• Saves the data when the delimiter is entered

Example

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Example (cont.)

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What are constants?

const PI = 3.14;

#define PI 3.14

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Operators and Operands“Don't cut the tree that shades you.”

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Operators Arithmetic :

• Unary Operators sign (+ or -)

• Algebraic operators

• + Addition

• - Subtraction

• * Multiplication

• / Division

• % Reminder

• ++ Increment

• -- Decrement

• += Add to the current content

• -= subtract from the current content

• *= , /= , ..

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Operators

Logical operators • o/p true or false

• ! NOT

• && AND

• || OR

• > greater than

• < less than

• >= greater than

• <= less than

• == equal

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Operators

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Operators

Conditional operator (?) :

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Operators

Explicit type casting operator • Converts a datum of a given type to another.

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Operator Precedence

Operator classification Operators

parentheses ( )

postfix operators [] x++ x--

unary operators ++x --x +x -x !

creation or cast new (type)x

multiplicative * / %

additive + -

relational < > >= <=

equality (boolean) = = !=

logical AND &&

logical OR ||

assignment =

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Example

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Example

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Example

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Control Statement

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Flow of the Control

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Control Statements

Ways for a programmer to control what pieces of the program are to be executed at certain times.

branching statements and loops.

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Branching Statement

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Example

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Nesting Branch

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Switch Statement

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Switch Statement

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Reading Materials

Chapters 1, 2 and 3, 5 (till 5.3).