concept programing

Chapter 2INTRODUCTORY CONCEPTS

Electrical Engineering Department MOHD NASRI BIN HASHIM

Faculty of Information Technology and Multimedia, 2008/2009

Learning Outcomes:

◊ Understand Constants and Variables◊ Understand Data Types◊ Understand Operators and Expressions

EC201 Fundamental Programming


Keyword

intThe acronym for integer

voidRefer to the function that will

not return any value

case default switch break

for continue float double

return while if do int

Example:


Constants and Variables (Identifier)


Identifier

Representing particular name in programmingStore values to be used in programmingRefers to the storage in computer

Standard identifier

User-definedidentifierType




Special built-in wordsReferred as function name which will called from C library

Standardidentifier

printf() scanf()puts() gets()

Identifier




Example..#include <stdio.h>

#include <conio.h>

#define PI 3.142 //define the constant value, PI=3.142

void main()

{

float radius, area;

printf("\nEnter radius: ");

scanf("%f",&radius);

area = PI * radius * radius;

printf("Area = %.2f \n",area);

printf("Press a key to finish.\n");

getch(); //to handle the screen

}



Name given to the declaration of data to be used in program Refer to the storage nameStore data values/result/output

User-definedidentifier

Constant VariableType

Identifier




User-definedidentifier

Identifiers name can only consists of name, number and underscoreIdentifiers name cannot be started with numbersSymbol cannot be used in identifier nameCannot contains spaces between two identifiers nameIdentifiers name should be uniqueIdentifiers is not case sensitive

RULES

Identifier




UThM DIT1064 Seven_eleven integer

Valid identifiers

8Century BIT 1033 Two*four

‘Sixsense’ void

Invalid identifiers

Identifier Example:

WHY?

WHY?

WHY?WHY?

WHY?




Name which used to store data valueRefer to name of one cell in computer storageContants value is fixed

Constant

Identifier

How to give name to a constant value?

Follow identifiers rules




const data_type const_name = const_value;

Declaration format:

const float pi = 3.142;Reserved word

Data type

1

Constant name

Constant Value




#define const_name const_value;

Declaration format:

#define pi 3.142;Reserved word

2

Constant n

ame

Constant value




Example..



#define minimum 0;#define MAX 100;

const int counter = 100;const char alphabet = ‘J’;const float value = 4.5;

Example of constant:




data_type variable_name;

Name which used to store data/input valueRefer to the name of one cell in computer storageVariable’s value can be modified/changed during execution

Variable

Declaration Format:

Identifier




Declaration Example

int number;

float weight;

char alphabet;

Declaration of a variable number of integer data type.

Declaration of a variable weight offloating point data type.

Declaration of a variable alphabet of character data type.




Variable/constant declaration example

//Variable and constant declration#include <stdio.h>

int number;float weight;

void main(){ const float pi =3.142;

int bilangan; float berat; char abjad; }

Constant declaration

Variable declaration

Variable declaration




Variable and constant declaration example:

//Variable and constant declaration#include <stdio.h>

const float pi=3.142;

void main(){ int bilangan, bil, bilang;

float berat, kg; char A; }




Assigning value to variables

#include <stdio.h>

void main(){

int number = 10; float weight; weight = 60.00;

printf(“Enter the value of number :”); scanf(“%d”,&number);

number = 50.00;}

Initialize a variable

Interactive

Example:

Initialize a variable




Represents types of data can be stored in computer.Types of data to be stored and used in programming should be informed to the compiler/system

Types

Integer

Floatingpoint

Character

Data Types


Data Types


Data TypesRepresents any round number with +/- values.Divided into short and long integer.Reserved word for integer – intValid until 5 places of integer number.

Integer

Example:age is used to represent the age of students between 18 and 25 years old. The declaration for thevariable is as follow:

int age;


Data Types


Data TypesRepresents any floating point numbers +/-Reserved word– double /float

Floating number

Example:height is used to represent the student’s height between 150 cm and 180 cm. The declaration for thevariable is as follow:

float height;


Data Types


Data Types

Represents character data.Reserved word – char

Character

Example:gender is used to represent the gender of a student. The declaration for the variable is as follow:

char gender;


Data Types


Determine whether the following identifiers is valid or invalid. Give reason for invalid cases.

1) Parit Raja

2) 20thCentury

3) int

4) INTEGER

5) _BMW2003

6) Reservedword

7) BIT1033

8) markah_pelajar

9) jam*kredit

10) printf

Exercise:


Example..


Write a suitable variable declaration for each of the following statement:

i. Salary of an employee

ii. Student’s mark for programming subject

iii. ATM pin number

iv. Phone number

v. Price of one item

vi. Bus seat number

vii. Student name

Exercise:


Example..


Given the value of x is 10 and a is 12, find the result of the following equation:

y = 2x + a - 6

Based on the following problem, determine the appropriate

variables can be declared:

Exercise:


Example..


Mrs Leeya needs to determine her students grade for programming subject based on the mark scored duringfinal examination. The ‘A’ grade will be given if the markscored is between 85 to 100. If a student has scored 90 marks, what is the grade should Mrs Leeya give to thestudent?



Exercise:


Example..




Exercise:

A box has height, width and length. Calculate the volume of a box.


Example..


Uncle Degawan wants to buy 5 tins of paint from Cinda’s shop. The price of each tin of the paint is RM 15.60. Calculate the price which Uncle Degawan haveto pay for all the tin of paints he bought.



Exercise:


Example..

30

Operators and Expressions


Expressions

Combination of Operators and Operands

Example 2 * y + 5

Operands

Operators



a) Operand A quantity or function upon which a mathematical or logical operation is performed




b) Operator An operator is a symbol which helps the user to command the computer to do a certain mathematical or logical manipulations. Operators are used in C language program to operate on data and variables. C has a rich set of operators which can be classified as



Arithmetic

Relational

Logical

Assignment

Increment and Decrement


i. Arithmetic- All the basic arithmetic operations can be carried out in C. All the operators have almost the same meaning as in other languages. Both unary and binary operations are available in C language. Unary operations operate on a singe operand, therefore the number 5 when operated by unary – will have the value –5



Operator Meaning

+ Addition or Unary Plus

– Subtraction or Unary Minus

* Multiplication

/ Division

% Modulus Operator


Example : There are two integer variables a and b. If the starting value of a=7 and b=2, the result will be:

Expression Value

a – b 5

a + b 9

a * b 14

a / b 3

a % b 1



Faculty of Information Technology and Multimedia, 2008/2009 EC201 Fundamental Programming


Integer Arithmetic When an arithmetic operation is performed on two whole numbers or integers than such an operation is called as integer arithmetic. It always gives an integer as the result. Let x = 27 and y = 5 be 2 integer numbers. Then the integer operation leads to the following results.

x + y = ?x – y = ?x * y = ?x % y = ?x / y = ?

In integer division the fractional part is truncated

32221152



ii. Relational OperatorOften it is required to compare the relationship between operands and bring out a decision and program accordingly. This is when the relational operator come into picture. C supports the following relational operators.

Operator Meaning

< is less than

<= is less than or equal to

> is greater than

>= is greater than or equal to

== is equal to

!= is not equal to


Operators and ExpressionsGiven below is a list of examples of relational expressions and evaluated values.

6.5 <= 25 TRUE -65 > 0 FALSE 10 < 7 + 5 TRUE

** The result of evaluation of a relational operation is either True (represented by 1) or false (represented by 0).

For example, if a = 7 and b = 5, then a < b yields 0

and a != b yields 1.


Operators and Expressionsiii. Logical OperatorC has the following logical operators, they compare or evaluate logical and relational expressions.

Operator Meaning

&& AND

|| OR

! NOT


Operators and ExpressionsLogical AND (&&) This operator is used to evaluate 2 conditions or expressions with relational operators simultaneously. If both the expressions to the left and to the right of the logical operator is true then the whole compound expression is true. Example

a > b && x = = 10 The expression to the left is a > b and that on the right is x == 10 the whole expression is true only if both expressions are true i.e., if a is greater than b and x is equal to 10. Logical OR (||) The logical OR is used to combine 2 expressions or the condition evaluates to true if any one of the 2 expressions is true. Example

a < m || a < n

The expression evaluates to true if any one of them is true or if both of them are true. It evaluates to true if a is less than either m or n and when a is less than both m and n.



Logical NOT (!) The logical not operator takes single expression and evaluates to true if the expression is false and evaluates to false if the expression is true. In other words it just reverses the value of the expression. For example ! (x >= y) the NOT expression evaluates to true only if the value of x is neither greater than or equal to y


The result of logical operation on a and b are summarized as below:-



Variable Expression

A B A && B A || B !A

T T T T F

T F F T F

F T F T T

F F F F T


Operators and Expressions4. Assignment OperatorsC provides several assignment operators for abbreviating assignment expressions. For example the statementc = c + 3;can be abbreviated with the addition assignment operator += asc += 3;The += operator adds the value of expression on the right of the operator to the value of the variable on the left of the operator and stores the result in the variable on the left of the operator. Any statement of the formVariable = variable operator expression;Where operator is one of the binary operators +, -, *, / or %, can be written in the formVariable operator = expression;Thus the assignment c += 3 adds 3 to c. Table shows the arithmetic assignment operators, sample expressions using these operators and explanations.



Assignment operator

Sample expression

Explanation Assigns

Assume: int c = 3, d = 5, e = 4, f = 6, g = 13

+= c += 7 c = c + 7 10 to c

-= d -= 4 d = d – 4 1 to d

Assignment operator

Sample expression

Explanation Assigns

*= e *= 5 e = e * 5 20 to e

/= f /= 3 f = f / 3 2 to f

%= g %= 9 g = g % 9 3 to g


Operators and Expressions5. Increments and Decrement Operators

Operator Sample expression

Explanation

++ ++a Increment a by 1 then use the new value of a in the expression in which a resides

++ a++ Use the current value of a in the expression in which a resides, the increment a by 1 (Still remain same number)

-- --b Decrement b by 1 the use the new value of b in the expression in which b resides

-- b-- Use the current value of b in the expression in which b resides, then decrement b by 1 (Still remain same number)


Operators and Expressions5. Increments and Decrement Operators

#include <stdio.h>int main(void);{int j = 5, k = 5, l = 5, m = 5;printf("j: %d\t k: %d\n", j, k);printf("j: %d\t k: %d\n", j++, k--);printf("l: %d\t m: %d\n", l, m);printf("l: %d\t m: %d\n", ++l, --m);}

Output:j: 5 k: 5j: 5 k: 5l: 5 m: 5l: 6 m: 4


HIERARCHY OF OPERATOR• The hierarchy of operator precedence form

highest to lowest is summarized below:

Operator Category Operator

Unary - - - + +

Arithmetic multiply, devide, remainder

* / %

Arithmetic add and subtract + -

Relational operators < <= > >=

Equality operators = = ! =

Logical AND &&

Logical OR ||



Find the answer using the hierarchy of operator.

Use: a=12, b=2, c=3a) X = a % bb) X = a /bc) X = a % b / cd) X = a / b % c


Exercise:

Example..


EXERCISE 1:

int a=5, b=2, c=3, d=4;

float answer;

answer = (a % c)* (d+b) * d / (a-c);

printf("The answer is : %.3f",answer);

printf("\n");

EXERCISE 2:

int m;int a=100, b=5, c=3, d=2, x=3;

m = a + b * c / d – x++;

printf(The answer is : %d",m);printf(/n);

Example..

Exercise:


answer=24 m=104


Consider the following example:

2*3+4/2 > 3 AND 3<5 OR 10<9

[2*3+4/2] > 3 AND 3<5 OR 10<9

[[2*3]+[4/2]] > 3 AND 3<5 OR 10<9

[6+2] >3 AND 3<5 OR 10<9

[8 >3] AND [3<5] OR [10<9]

True AND True OR False

[True AND True] OR False

True OR False

True EC201 Fundamental Programming

Example..

Exercise:

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concept programing