KUKUM Sem1-05/06EKT120: Computer Programming1 Week 2.

KUKUM Sem1-05/06

EKT120: Computer Programming

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Week 2

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Outline Identifiers and reserve words Program comments Preprocessor directives Data types and type declarations Operators Formatted input and output Program debugging

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Operators Operators tell the computer how to

process the data. It connects data in the expression

and equation Types of operators used in

calculation and problem solving include Mathematical Relational Logical

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Operators continue…. Two concepts related to operator are

Operand Resultant

Operands are the data being process Resultant is the answer that result when the

operation is complete. Example 5 + 7 = 12 Operands ara 5 and 7 Operator is + Resultant is 12

Operands can be constant or variable Data types of resultant and operands will

depend on the operator

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Types of Operator Mathematical operators

Addition (+) Subtraction (-) Multiplication (*) Division (/) Integer division (\) Modulo division (MOD) Powers (^) Functions

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Types of Operator Relational operators

Equal to Less than Greater than Less than or Equal to

The resultant of relational operation is logical data type i.e. TRUE or FALSE

The next set of actions will depend on the result of the relational expression

E.g. Balance > 500, if the expression TRUE withdraw 100, if the expression FALSE withdraw 50.

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Types of Operators Logical Operator

OR AND Not

Use to connect relational expression (decision-making expression)

To perform operation on logical data

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Example of OperatorOperator Computer Symbol Example

Mathematical Operation Resultant

Addition + 3.0 + 5.2 8.2

Subtraction - 7.5 – 4.0 3.5

Multiplication * 8.0 * 5.0 40.0

Division / 9.0/4.0 2.25

Integer Division \ 9\4 2

Modulo division MOD 9 MOD 4 1

Power ^ 3^2 9

Relational

Equal To = 5=7 FALSE

Less Than < 5<7 TRUE

Greater Than > 5>7 TRUE

Less than or equal to

<= 5< = 7 FALSE

Greater than or equal to

>= 5>=7 FALSE

Not Equal to <> 5<>7 TRUE

Logical

Not NOT NOT TRUE FALSE

And AND TRUE AND TRUE TRUE

Or OR TRUE OR FALSE TRUE

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Operator Hierarchy (Precedence)Order of Operation Operand Data Type Resultant Data Type

( ) Reorders the hierarchy; all operations are completed within the parentheses using the same hierarchy

1. Functions

Mathematical Operators

2. Power Numerical Numerical

3. \, MOD Numerical Numerical

4. *, / Numerical Numerical

5. +, - Numerical Numerical

Relational Operators

6. =, <, >, <=, >=, <> Numerical, string, character

Logical

Logical Operator

7. NOT Logical Logical

8. AND Logical Logical

9. OR Logical Logical

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Expression & Equation Expression and Equation make up the

instructions in the solution to a computer problem

Expression processes data (the operand) through the operators. E.g. LENGTH * WIDTH

Equation stores the resultant of an expression in a memory location in the computer through the (=) sign (assignment symbol) E.g. AREA = LENGTH * WIDTH The resultant of expression LENGTH * WIDTH will be stored

in a location called AREA

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Normal equation

Appropriate Computer Equation X* (3*Y+4)-4*Y/(X+6)

Setting up Numerical Expression

X+6X(3Y+4) - 4Y

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Evaluating Mathematical Expression Consider

5*(X+Y)-4*Y/(Z+6) Value of X = 2, Y=3,

Z=6 Evaliation

5 * (X + Y) – 4 * Y / (Z+6)

1 23 4

56

Operation Resultant

1. X+Y 5

2. Z+6 12

3. 5 * resultant of 1 25

4. 4 * Y 12

5. Resultant of 4 / resultant of 2 1

6. Resultant of 3 – Resultant of 5 24

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Evaluation Relational Expression Expression

1 23

4

Operation Resultant

1. A < B FALSE

2. C OR D TRUE

3. NOT the resultant of 1 TRUE

4. Resultant of 3 AND Resultant of 2

TRUE

NOT (A < B) AND (C OR D) A = 4, B=2

C = TRUED = FALSE

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Getting Started With C//Program name : program1.c//Programmer : Salina//This program Print Welcom to KUKUM//Calculate A = B * K;//Print AnswerA

#include <stdio.h>int main(void){

float A, B;const float K=0.05;

printf(“Welcome To KUKUM”); B = 400;

A = B * K;printf(“\nValue of A : %5.2f”, A);return 0;

}

The terms void indicates we receive nothing from OS. int at the beginning return an integer

to OS

Variable &

constant declaratio

n

begin

end

Return 0(int) to OS

body

Comments

Preprocessor directives

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Identifiers & Reserve Words Identifiers

labels for program elements, such as variable and constant name

case sensitive can consists of capital letters[A..Z], small

letters[a..z], digit[0..9], and underscore character _ First character MUST be a letter or an underscore No blanks Reserve words cannot be used as identifiers

Reserve words already assigned to a pre-defined meaning eg: delete, int, main, include, double, for, if, float etc.

(Pleased refer text book) We cannot use the reserve word as our variable.

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Program comments Starts with /* and terminate with

*/ OR Character // start a line comment,

if several lines, each line must begin with //

Comments cannot be nested /* /* */*/

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Preprocessor directives An instruction to pre-processor Standard library header (p154,Deitel) E.g. #include <stdio.h>

for std input/output #include <stdlib.h>

Conversion number-text vise-versa, memory allocation, random numbers

#include <string.h> string processing

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Data Types & Mem. Alloc.

Data Type

DescriptionSize (byte

s)

charA single character. Internally stored as a coded integer value (refer to ASCII table).

1

intInteger quantity. Can be represented in signed or unsigned form (with the unsigned keyword).

4

float Floating-point number. Set of real numbers. 4

doubleA more precise version of float. Has larger dynamic range and better representation of decimal points.

8

boolBoolean representation of logic states. Can only be assigned true (1) or false (0).

1

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Type declarations Before we can use the variables in

the program, we must declare them first

float income;float net_income;

int index =0, count =0; char ch=‘a’, ch2; const float epf = 0.1, tax = 0.05;

float income, net_income;

Declare and initialize

Named constant declared and

initialized

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Types of operators Types of operators are:

Arithmetic operators (+ , - , * , / , %)

Relational operators (> , < , == , >= , <=, !=)

Logical operators (&& , ||) Compound assignment operator

(+=, -=, *=, /=, %=) Binary operators: needs two operands Unary operators: single operand Bitwise operators: executes on bit level

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Arithmetic Operators Used to execute mathematical

equations The result is usually assigned to a

data storage (instance/variable) using assignment operator ( = )

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C OperatorsOperator C Language Symbol Example

Mathematical Operation Resultant

Addition + 3.0 + 5.2 8.2

Subtraction - 7.5 – 4.0 3.5

Multiplication * 8.0 * 5.0 40.0

Division / 9.0/4.0 2.25

Integer Division (Quotion \ 9\4 2

Modulo division % 9 % 4 1

Power ^ 3^2 9

Relational

Equal To == 5==7 FALSE

Less Than < 5<7 TRUE

Greater Than > 5>7 TRUE

Less than or equal to <= 5< = 7 FALSE

Greater than or equal to >= 5>=7 FALSE

Not Equal to != 5!=7 TRUE

Logical

Not ! NOT TRUE FALSE

And && TRUE AND TRUE TRUE

Or || TRUE OR FALSE TRUE

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Exercise on arithmetic operators Given x = 20, y = 3 z = x % y = 20 % 3

= 2 (remainder)

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Relational and Logical Operators Previously, relational operator: >, < >=, <=, == , != Previously, logical operator:

&&, || Used to control the flow of a

program Usually used as conditions in

loops and branches

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More on relational operators Relational operators use

mathematical comparison (operation) on two data, but gives logical output

e.g1 let say b = 8, if (b > 10) e.g2 while (b != 10) e.g3 if(kod == 1)

print(“Pegawai”); Reminder: Don’t confuse == (relational op.) with = (assignment op.)

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More on logical operators Logical operators are manipulation

of logice.g1 let say b=8, c=10,

if ((b > 10) && (c<10))e.g2 while ((b==8) ||(c > 10))e.g3 if ((kod == 1) && (salary > 2213))

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Truth table for &&(logical AND) operator

exp1 exp2 exp1 && exp2

false false false

false true false

true false false

true true true

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Truth table for ||(logical OR) operator

exp1 exp2 exp1 || exp2

false false false

false true true

true false true

true true true

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Compound assignment operator To calculate value from expression and

store it in variable, we use assignment operator (=)

Compound assignment operator combine binary operator with assignment operator

E.g. val +=one; is equivalent to val = val + one; E.g. count = count -1; is equivalent to

count -=1;count--;--count;

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Unary Operators Obviously operating on ONE

operand Commonly used unary operators

Increment/decrement { ++ , -- } Arithmetic Negation { - } Logical Negation { ! }

Usually using prefix notation Increment/decrement can be both

a prefix and postfix

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Unary Operators (Eg.) Increment/decrement { ++ , -- }

prefix:value incr/decr before used in expression

postfix:value incr/decr after used in expression

Logical Negation { ! } bool isDinnerTime = true; bool isLunchTime = !isDinnerTime;

val=5;

cout<<++val;

Output:

6

val=5;

cout<<--val;

Output:

4val=5;

cout<<val++;

Output:

5

val=5;

cout<<val--;

Output:

5

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Operator Precedence & symbol in C languageOrder of Operation Symbol in C

( ) Reorders the hierarchy; all operations are completed within the parentheses using the same hierarchy

1. Functions

Mathematical Operators

2. Power ^

3.Integer division, modulo \, %

4. Multiplication, division *, /

5. Addition, substraction +, -

6. equal, less than, greater than, less than equal, greater than equal, not equal

==, <, >, <=, >=, !=

Logical Operator

7. NOT !

8. AND &&

9. OR ||

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Formatted Output with printf To display result of the program

can be done by using keyword printf and operator as shown below:

printf(“formating”,variable) ;//this is variable declarationint a, b; //Line 1char grade; //Line 2//examples of input and output statements a = 25; grade = ‘A’;//Line3printf(“a = ”,a) ; //Line 4printf(“Enter two integers: ”) ;//Line 5scanf (“%d%d”,&a,&b) ;printf(“The numbers you entered are %d %d”,a,b); //Line 6printf(“Your grade is %c “,grade); //Line 10

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Formatted Output with printf-cont

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End Week 1 – Session 2

Q & A!

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KUKUM Sem1-05/06EKT120: Computer Programming1 Week 2.

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