P5 Operators and Expressions

8/3/2019 P5 Operators and Expressions

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OPERATOROPERATOR

Symbol that operates on a certain data

type.

Example:+ -addition operator

Can operate on integer, character and real

Expression-combination of variables,constants and operators

Every expression evaluates to a value


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CONCEPT OF EVALUATIONCONCEPT OF EVALUATION

= Assignment operator

Assigns the value of the variable on the left hand

side to that of the right hand side.

Left hand side of the assignment operator and

the right hand side together form an expression.

For example:

int i,j;Valid expression would be: i=5;

j=i=5;


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TYPES OF OPERATORSTYPES OF OPERATORS

Classified based on their utility and action.

Arithmetic operators

Relational operators

Logical operators


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ARITHMETIC OPERATORSARITHMETIC OPERATORS

Perform arithmetic operations

Operates on any data type

List of arithmetic operators+ - addition

- - subtraction

* - multiplication

/ - division

% - modulo division


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Integer ArithmeticInteger Arithmetic

If operands such as x and y are integers,

then arithmetic operation on them is called

integer arithmetic. Always yields an integer value.

Example:

int x=16,y=5; Integer arithmetic on x and y are as

follows:


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Integer ArithmeticInteger Arithmetic

x=16,y=5;

x + y = 21;

x y = 11;

x * y = 80;

x / y = 3;/*result is truncated, decimal part is

discarded*/

x % y =1;/*result is the remainder of the integerdivision, sign of the result=sign of the

first operand*/


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Integer DivisionInteger Division

Result is truncated towards zero if both the

operands are of the same sign, and is

dependent on the machine if one of the

operands is negative.

Example:

6 / 8 = 0;

-6 / -8 = 0;

-6 / 8 = 0 or -1 /*machine dependent */


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Floating point ArithmeticFloating point Arithmetic

Operands are of data type float

% operator is not applicable

Example:float a=14.0,b=4.0;

P = a / b = 3.500000

Q = b / a = 0.285714R = a + b = 18.00000


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Mixed Mode ArithmeticMixed Mode Arithmetic

Operation between an integer and real

always yields a real result.

In this operation the integer is firstpromoted to a real and then the operation

is performed. Hence the result is real.


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Mixed Mode ArithmeticMixed Mode Arithmetic


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Relational OperatorsRelational Operators

Used to compare

arithmetic, logical and

character

expressions. Condition is evaluated

zero- false

one - true.

Operator Meaning

< Less than

> Greater than

= Greater than

or equal to== Equal to

!= Not equal to


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Logical OperatorsLogical Operators

Used to compare or evaluate logical and

relational expressions.

Operator Meaning

&& Logical AND

!! Logical OR! Logical NOT


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Type conversion in assignmentsType conversion in assignments

Sometimes type of the variable on the left

hand side may not be the same.

Value is promoted or demoted dependingon the value on the left hand side of =.

Example

int i ;

float b ;

i = 3.5 ; /*Float is demoted to int and only 3 is stored*/

b = 30 ; /*30 is promoted to float and 30.0000 is stored*/


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Type conversion in assignmentsType conversion in assignments

Let us consider an complex instruction

float a, b, c ;

int s ;

s = a * b * c / 100 + 32 / 4 - 3 * 1.1 ; /* answer value of float type is

demoted to int and stored in s */

K is an integer

A is an real


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Hierarchy of OperationsHierarchy of Operations

Priority or precedence in which operations are

performed arithmetic statements.

Within parenthesis hierarchy is same.But,if there is more than one set ofparenthesis, innermost parenthesis would be performed first.


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Determine hierarchy and evaluate the

following expression

i = 2 * 3 / 4 + 4 / 4 + 8 - 2 + 5 / 8

i = 6 / 4 + 4 / 4 + 8 - 2 + 5/ 8 operation: *

i = 1 + 4 / 4 + 8 - 2 + 5 / 8 operation: /

i = 1 + 1+ 8 - 2 + 5 / 8 operation: /

i = 1 + 1 + 8 - 2 + 0 operation: /

i = 2 + 8 - 2 + 0 operation: +

i = 10 - 2 + 0 operation: +i = 8 + 0 operation : -

i = 8 operation: +


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Evaluate

kk = 3 / 2 * 4 + 3 / 8 + 3

kk = 1 * 4 + 3 / 8 + 3 operation: /kk = 4 + 3 / 8 + 3 operation: *

kk = 4 + 0 + 3 operation: /

kk = 4 + 3 operation: +kk = 7 operation: +


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Converting General ArithmeticConverting General Arithmetic

Statement to C StatementStatement to C Statement


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Associativity of operatorsAssociativity of operators

Expression contains two operators of equalpriority, then it is solved using Associativity.

It can be of two types.

Left to Right

- Left operand must be unambiguous

Right to Left- Right operand must be

unambiguous


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Consider the expression

a = 3 / 2 * 5 ; /* there is a tie between *

and / operator */


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Consider one more expression

a = b = 3 ; /* both = has the same priority*/


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Another expression

z = a * b + c / d ; /* / and * has same priority

and same Associativity */


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P5 Operators and Expressions

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