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Chapter 4

Expression & Operators

Aim

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To give understanding on:Expression and operator conceptmath.h and stdlib.h built-in function

Students should be able to:understand concepts and fundamentals in expression/operator.write expression in C programming language

Objective

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Given the following statement :

2x + 3 – z = y

expression

Introduction to Expression

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Process involves in money

withdrawal scenario

balance – withdrawed money = current balance

Introduction to Expression

Expression in C :

bakiTerkini =wangKeluar – bakiSemasa;

What is Expression?

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Expression

Combination or more than one variable or

Constant (operand) which separated by

operator

x + 3 - z

Operand

Operatorexample

Consists of arithmetic

relational

logical

Introduction to Expression

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Arithmetic Expression Mathematic ExpressionKnown as

usingArithmetic Operator

Unary operator Binary operatorRepresents by

Operator Meaning

- negative

+ positive

-- decrement

++ increment

Represents by

Operator Meaning* multiply

/ divide

+ add

- subtract

% modulus

Arithmetic Expression

Unary Operator

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Unary Operator Operates for one operand

example

a = -20; a -20

Computer memory cell

b = +15; b +15

Increment Decrement

prefix ++c; --c;

postfix c++; c--;

Arithmetic Expression

Unary Operator

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Example 1:

int A = 5;

++A;

printf(“%d”, A); output ?

A--;

printf(“%d”,A); output ?

A++;

printf(“%d”,A); output ?

Arithmetic Expression

Unary Operator

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Example 2:

int A ;

A=6;

printf(“%d”,3 + --A); output ?

printf(“%d”, A); output ?

A=6;

printf(“%d”, 3 + A--); output ?

printf(“%d”, A); output ?

Arithmetic Expression

Unary Operator

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Example 3:

Given the value of num1 = 8 .Determine the value of num2 after the execution for each of the following statements:

num2 = num1++ - 2;

num2 = num1;

num2 = ++num1 – 3;

num2 = num1-- +1;

Arithmetic Expression

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Binary Operator

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Binary Operator Located between constants or variables or both combination

exampleA + z

operator

operand

Arithmetic Expression

Binary Operator

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Multiplication Use symbol “ * ”

exampleA * z

operator

operand

Mathematic

2x + y

Arithmetic Expression

2 * x + y

Arithmetic Expression

Binary Operator

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Divide Use symbol “/”

exampleA / z

operator

operand

Mathematic

2 : y

Arithmetic Expression

2 / y

Arithmetic Expression

Binary Operator

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Modulus Use symbol “%”

exampleA % z

operator

operand

Return a balance when 2 numbers is divided

Can only be used with an integer variable

Arithmetic Expression

Binary Operator

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Example:int A, B;

float C;

A= 2;

B= 5;

C= 2.4;

B% A;

C % A;

Valid! Answer is 1

Invalid! C is float

Arithmetic Expression

Assignment Statement

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Used to store value/result of process to a variableUse operator symbol =

Assignment statement

Double assignmentstatement

Compound assignmentstatement

Arithmetic Expression

Assignment Statement

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Format /sintax :

variable = value;

variable = constant; or variable = variable;

variable = expression;

Example :1.average= ( 6 + 5) * 4;

2.grossSalary = 1500;nettSalary = grossSalary + 200;

3.price= 50.00;pay = price;

`

44average

grossSalary1500

nettSalary 1700

price

pay

50.00

50.00

Arithmetic Expression

Compound Assignment Statement

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Use more than one operator (=) Example :

int a = b= c = d = e = 250;int b =2, number =0, total = 0,average =3;number = b++ = 10;int age = workHour = 0;

Arithmetic Expression

Compound Assignment Statement

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To combine two different operator together.To simplify arithmetic operatorOriginal function of operator does not affectedAllowed combination are as follow:

Arithmetic Expression

+= , -= , *= , /= , %=

Function

operator:

Compound Assignment Statement

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Example :

Assignment

Operator

Expression Meaning

+= total + = 300 total = total+ 300

-= total - = count+ 300 total = total - (count + 300)

*= total *=300 total = total * 300

/= total /= count– 10 total = total / ( count –10)

%= total % = 7 total = total % 7

Arithmetic Expression

Arithmetic Operator Precedence Rules

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Compiler will follows the following precedence to execute the arithmetic expression based on priority.

Operator Arrangement/Priority

(if appears more than once in a statement)

( ) Left to right

++, -- Right to left

*, /, % Left to right

+, - Left to right

Arithmetic Expression

Arithmetic Operator Precedence Rules

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Example:

1. 5 + 2 * 6 – 4 / 2

5 + 12 - 4 / 2

5 + 12 - 2

17 - 2

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2. 3 * 4 / 2 + ( 3 –1)

3 * 4 / 2 + 2

12 / 2 + 2

6 + 2

8

Arithmetic Operator

Arithmetic Operator Precedence

Rules

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Example:

3. Prefix unary arithmetic expression

int kira = 5, nilai pertama = 10;

nilai_kedua = 5 * --kira + nilai_pertama;

printf(“%d %d”, kira, nilai_kedua);

Output:

4 30

Arithmetic Expression

Arithmetic Operator Precedence

Rules

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Example:

3. Prefix unary arithmetic expression

int kira = 5, nilai pertama = 10;

nilai_kedua = 5 * kira-- + nilai_pertama;

printf(“%d %d”, kira, nilai_kedua);

Output:

4 35

Arithmetic Expression

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Mathematic Library Function

•Diwakili oleh perpustakaan piawai matematk iaitu math.h•Dipanggil bersama #include•Antara fungsi perpustakaan matematik yang penting:

Fungsi Tujuan

sqrt(x) Kembalikan nilai puncagandadua x di mana x >= 0

pow(x) Kembalikan x ganda y

cos(x) Kembalikan cos x di mana x di dalam radian

sin(x) Kembalikan sin x di mana x di dalam radian

tan(x) Kembalikan tan x di mana x di dalam radian

Arithmetic Expression

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Mathematic Library FunctionExample:

#include<stdio.h>#include <math.h>

void main(){

int x = 16, y ;y = sqrt(x);printf(“%d”,y);

}

Output :

4

Arithmetic Expression

Exercise:

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1. Convert the following mathematic expression to a valid arithmetic expression :

a) b = 3 + b b) x = (a – b)(a – c2)a + 4

c) d = (3e – d) - ( 4 – 3c3 ) d) r = 2s + 3(s – 9)x – 9 4y s

2. Given a= 3, b = 5, c=1. What is the output of the following expression?

a. ( 6 * c – 6 / a) - b b. (5 * c) +( a* b / b)

c. ++a d. c + a * c / (3 * c)

Arithmetic Expression

Exercise:

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Assume i,j and k are integer variables with i = 5 and j=3. Determine what is the value for each of the following statement:a) k = j++; d) k = ++j;b) k = i * j--; e) k = i * --j;c) k = j + i * j++; f) k = 27 / j++ - 16 % i;

Arithmetic Expression

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Relationalexpression

use Relational operator

Combination of more than one statement

variable vs variable

variable vs constant

constant vs constant

Can consists of

produce

0 (if false) 1(if true)

Relation Expression

Relational Operator

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Operator Description

= = Equal to

> Greater than

< Less than

>= Greater than or equal

<= Less than or equal

!= Not equal

Relation Expression

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int a=6, b =1, c = -2;

1) a+ b == c 2) a != b

6 + 1== -2 6 != 17 == -2

Answer: 0(False) Answer : 1 (True)

P/s:a, b and c are variables,Replace with the given values

Example 1:

Relation Expression

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int a=6, b =1, c = -2;

3) b < a 4) b + c <= a

1 < -2 1 + -2 < 6-1 < 6

Answer: 0 (False) Answer : 1 (True)

Example 2 :

Relation Expression

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int a=10, b = 3, c = 7;

(a+b >= 3*c)==( a != 2*c+b)

(10+3 >= 3*7)==(a != 2*c+b)(13 >= 21)==(10 != 14+3)(13 >= 21)==(10 != 17)0 == 10 (false)

P/s:

Relational operator has less priority than other operators.Start evaluating from left to right.

Example 3:

Relation Expression

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An example program which uses relational expression

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

printf(“\nPlease enter your age >>”);scanf(“%d”,&age);

if (age > 21)

printf(“\nYou are qualified to vote”);

}

Relational expression

Relation Expression

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Logical expression

use

Logical Operator

Combination of one or more expressions

Relational expr. vs logical expr.

Relational expr. vs variable

Relational expr. vs constant

Can consists of

produces

0 (if false) 1(if true)

Logical Expression

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Logical Operator

Operator Description

&& AND

|| OR

! NOT

Logical operator && dan || is used between 2 or morerelational expression

Logical Expression

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Logical operator truth table for AND

Value 0 1

0 0 0

1 0 1

AND (&&) Logical Operator Result

False AND False False

False AND True False

True AND False False

True AND True True

Logical Expression

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Logical operator truth table for OR

Value 0 1

0 0 1

1 1 1

OR (||) Logical Operator Result

False OR False False

False OR True True

True OR False Trrue

True OR True True

Logical Expression

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Value Result

!0 1

!1 0

NOT(!)

Logical Operator Result

Not false True

Not true False

Logical operator truth table for NOT

Logical Expression

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Example 1:

Evaluate the following logical expression:

a) (2 < 5 ) && ( 5 < 10) b) (7 % 2 < 2) || ( 2 * 3 == 6)

1 && 1 (1 < 2) || (6 == 6)

1 1 || 1

1

Logical Expression

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Example 2:

Evaluate the following logical expression:

Given a = 3, b = 4;

c) !((5 * b <= 23 - a )) d) ! ((b +3 != 8) &&( 3 * a < 2))

!((5 * 4 <= 23 – 3)) !(( 7 != 8 ) && ( 9 < 2 ))

!(20 <= 20) ! ( 1 && 0 )

!(1) ! ( 0)

0 1

Logical Expression

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An example program which using Logical Expression:

#include <stdio.h>

void main()

{ int mark;

printf(“\nEnter your mark >>”);

scanf(“%d”,&mark);

if (mark >= 85 && mark <= 100)

printf(“\nGred A”);

else if( mark >=80 && mark <=84)

printf(“\nGred A-”);

}

Logical ExpressionLogical Expression

Exercise:

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1. Given with i=2, j = 5 and k = 15. Evaluate each of the following expression:a) i > j – k g) k == j + I * jb) i != k h) k <=k /jc) (i >= 1) && (j == 5) i) (j < i) || (k > j)d) !( i > j) j) (i >0) && (j <k) || (k <i)e) i < j < k k) i * k < k / jf) (i < j) && (j < k) i) i – j > k

2. Complete the following statements with suitable logical expression.

int angka1,angka2;

if (angka1 is less than or equal to angka2)

printf(“%d is less than or equal to %d”,angka1,angka2);

Logical Expression