The document explains various types of operators and expressions in programming, specifically in C language. It details operators such as arithmetic, relational, logical, assignment, increment/decrement, conditional, bitwise, and special operators, along with examples of their usage. Additionally, the document covers operator precedence and associativity relevant for evaluating expressions involving multiple operators.

1. Operators
and
Expressions
Unit 4

2. Operators
• Symbol that operates on certain data type or data item.
• Used in program to perform certain mathematical or
logical manipulations.
• Ex: in a simple expression 5+6, the symbol “+” is called
an operator which operates on two data items 5 and 6.
• The data items that operator act upon are called
operands.
Ashim Lamichhane 2

3. Expression
• An expression is a combination of variables,
constants and operators written according to
syntax of the language.
• Ex:
8+10 a+c*d a>b a/c
Ashim Lamichhane 3

4. • We can classify operators into
– Unary operators
• Which requires only one operand
• Ex. ++ , --, +,-
– Binary operators
• Which requires two operands
• Ex. +,-,*, / , < , > etc.
– Ternary operators
• Which require three operands
• Ex. “ ?: ” (conditional operator)
Ashim Lamichhane 4

5. • Ternary operators can be further classified
into following categories:
–Arithmetic Operators
–Relational Operators
–Logical Operators
–Assignment Operators
–Increment and Decrement Operators
–Conditional Operators
–Bitwise Operators
–Special Operators
Ashim Lamichhane 5

6. Arithmetic Operators
Assume variable A holds 10 and variable B holds 20
then
Operator Description Example
+ Adds two operands. A + B = 30
− Subtracts second operand from the first. A − B = 10
* Multiplies both operands. A * B = 200
/ Divides numerator by de-numerator. B / A = 2
% Modulus Operator and remainder of after an integer
division.
B % A = 0
++ Increment operator increases the integer value by
one.
A++ = 11
-- Decrement operator decreases the integer value by
one.
A-- = 9
Ashim Lamichhane 6

7. Integer Arithmetic
• Division Rule
– Int / int =int
– Float / float= float
– Int / float = float
– Float /int =float
Ashim Lamichhane 7

8. #include <stdio.h>
Void main() {
int a = 21; int b = 10; int c ;
c = a + b;
printf("Line 1 - Value of c is %dn", c );
c = a - b;
printf("Line 2 - Value of c is %dn", c );
c = a * b;
printf("Line 3 - Value of c is %dn", c );
c = a / b;
printf("Line 4 - Value of c is %dn", c );
c = a % b;
printf("Line 5 - Value of c is %dn", c );
c = a++;
printf("Line 6 - Value of c is %dn", c );
c = a--;
printf("Line 7 - Value of c is %dn", c );
}
Ashim Lamichhane 8

9. Relational Operators
Assume variable A holds 10 and variable B holds 20
Operator Description Example
== Checks if the values of two operands are equal
or not. If yes, then the condition becomes true.
(A == B) is not true.
!= Checks if the values of two operands are equal
or not. If the values are not equal, then the
condition becomes true.
(A != B) is true.
> Checks if the value of left operand is greater
than the value of right operand. If yes, then the
condition becomes true.
(A > B) is not true.
< Checks if the value of left operand is less than
the value of right operand. If yes, then the
condition becomes true.
(A < B) is true.
>= Checks if the value of left operand is greater
than or equal to the value of right operand. If
yes, then the condition becomes true.
(A >= B) is not true.
<= Checks if the value of left operand is less than
or equal to the value of right operand. If yes,
then the condition becomes true.
(A <= B) is true.
Ashim Lamichhane 9

10. #include <stdio.h>
main() {
int a = 21; int b = 10; int c ;
if( a == b ) {
printf("Line 1 - a is equal to bn" );
}
else {
printf("Line 1 - a is not equal to bn" );
}
if ( a < b ) {
printf("Line 2 - a is less than bn" );
}
else {
printf("Line 2 - a is not less than bn" );
}
if ( a > b ) {
printf("Line 3 - a is greater than bn" );
}
else {
printf("Line 3 - a is not greater than bn" );
}
/* Lets change value of a and b */
a = 5; b = 20;
if ( a <= b ) {
printf("Line 4 - a is either less than or equal to bn" );
}
if ( b >= a ) {
printf("Line 5 - b is either greater than or equal to bn" );
}
}
Ashim Lamichhane 10

11. Logical Operators
Assume variable A holds 1 and variable B holds 0
Operator Description Example
&& Called Logical AND operator. If both the
operands are non-zero, then the condition
becomes true.
(A && B) is false.
|| Called Logical OR Operator. If any of the two
operands is non-zero, then the condition
becomes true.
(A || B) is true.
! Called Logical NOT Operator. It is used to
reverse the logical state of its operand. If a
condition is true, then Logical NOT operator will
make it false.
!(A && B) is true.
Ashim Lamichhane 11

12. Void main() {
int a = 5; int b = 20; int c ;
if ( a && b ) {
printf("Line 1 - Condition is truen" );
}
if ( a || b ) {
printf("Line 2 - Condition is truen" );
}
/* lets change the value of a and b */
a = 0; b = 10;
if ( a && b ) {
printf("Line 3 - Condition is truen" );
} else
{
printf("Line 3 - Condition is not truen" );
}
if ( !(a && b) ) {
printf("Line 4 - Condition is truen" );
}
}
Ashim Lamichhane 12

13. Assignment Operators
Operator Description Example
= Simple assignment operator. Assigns values from
right side operands to left side operand
C = A + B will assign the
value of A + B to C
+= Add AND assignment operator. It adds the right
operand to the left operand and assign the
result to the left operand.
C += A is equivalent to C =
C + A
-= Subtract AND assignment operator. It subtracts
the right operand from the left operand and
assigns the result to the left operand.
C -= A is equivalent to C =
C - A
*= Multiply AND assignment operator. It multiplies
the right operand with the left operand and
assigns the result to the left operand.
C *= A is equivalent to C =
C * A
/= Divide AND assignment operator. It divides the
left operand with the right operand and assigns
the result to the left operand.
C /= A is equivalent to C =
C / A
%= Modulus AND assignment operator. It takes
modulus using two operands and assigns the
result to the left operand.
C %= A is equivalent to C =
C % A
Ashim Lamichhane 13

14. Increment And Decrement Operators
• Increment operator is used to increase the
value of an operand by 1
• Decrement operator is used to decrease the
value of an operand by 1
Operator Description Example
++ ++variable (prefix notation) Variable = variable + 1
++ variable++ (postfix notation) Variable= variable + 1
-- - -variable (prefix notation) Variable =variable - 1
-- variable- - (postfix notation) Variable =variable - 1
Ashim Lamichhane 14

15. void main(){
int a= 10;
clrscr();
printf("a =%d",a);
printf("a =%d",++a);
printf("a =%d",a++);
printf("a =%d",a);
}
Ashim Lamichhane 15

16. void main(){
int a= 10;
clrscr();
printf("a =%d",a);
printf("a =%d",++a);
printf("a =%d",a++);
printf("a =%d",a);
}
OUTPUT:
a=10
a=11
a=11
a=12
Ashim Lamichhane 16

17. Conditional Operator
• The operator pair “?:” is known as conditional operator.
• It takes three operands. Also called ternary operator.
• General form:
expression1 ? expression 2 : expression 3
• expression1 is evaluated first
If expression1 is true
then value of expression2 is the value of condition
expression
else
the value of expression3 is the value of conditional
expression
Ashim Lamichhane 17

18. void main()
{
int n1,n2, larger;
clrscr();
printf("Enter Two numbers:");
scanf("%d%d",&n1,&n2);
larger= n1>n2 ? n1 : n2;
printf("The larger number is %d", larger);
getch();
}
Ashim Lamichhane 18

19. Bitwise Logical Operator
• Bitwise operators are used for manipulating data at bit level.
• These operators are used for testing the bits or shifting them to the
left or to the right.
• Can be applied only to integer-type operands and not to float or
double.
• Three types of bitwise operators
– Bitwise logical operators
– Bitwise shift operators
– One’s complement operator
Ashim Lamichhane 19

20. Bitwise logical Operators
• Performs logical tests between two integer-type operands.
• These operators work on their operands bit-by-bit starting
from the least significant(i.e rightmost) bit.
• Three logical bitwise operators
– Bitwise AND(&)
– Bitwise OR( | )
– Bitwise Exclusive OR (^)
Ashim Lamichhane 20

21. Bitwise And (&)
• Logical ANDing between two operands.
• The result of ANDing operation is 1 if both the bits
have a value of 1; otherwise it is 0.
• Consider n1=60 and n2=15
– N1 0000 0000 0011 1100
– N2 0000 0000 0000 1111
• If n3= n1 & n2;
– n3  0000 0000 0000 1100
Ashim Lamichhane 21

22. Bitwise OR( | )
• ORing between two operands
• The result of Oring operations is 1 if either of the bits have
value of 1; otherwise it is 0.
• Consider n1=60 and n2=15
– N1 0000 0000 0011 1100
– N2 0000 0000 0000 1111
• If n3= n1 | n2;
– n3  0000 0000 0011 1111
Ashim Lamichhane 22

23. Bitwise Exclusive XOR ( ^ )
• The result of Exclusive ORing operations is 1 only
if one of the bits have a value of 1; otherwise it is
0.
• Consider n1=60 and n2=15
– N1 0000 0000 0011 1100
– N2 0000 0000 0000 1111
• If n3= n1 & n2;
– n3  0000 0000 0011 0011
Ashim Lamichhane 23

24. #include<stdio.h>
void main(){
int n1=60,n2=51,AND, OR, XOR;
AND= n1 & n2;
OR= n1 | n2;
XOR= n1 ^ n2;
printf("AND=%dn",AND );
printf("OR=%dn",OR );
printf("XOR=%dn",XOR );
}
Ashim Lamichhane 24

25. Bitwise Shift Operators
• Are used to move bit patterns either to the
left or to the right.
• There are two bitwise shift operators
– Left shift ( << )
– Right shift ( >> )
Ashim Lamichhane 25

26. • Left Shift ( << )
– Causes the operand to be shifted to the left by n
positions.
• operand << n
– The leftmost n bits in the original bit pattern will
be lost and the rightmost n bits empty positions
will be filled with 0’s.
– Ex n1=60
• Execute the statement n2= n1 <<3;
n1 0000 0000 0011 1100
Shift 1 0000 0000 0111 1000
Shift 2 0000 0000 1111 0000
Shift 3 0000 0001 1110 0000 (==n2)
Ashim Lamichhane 26

27. • Right Shift ( >> )
– Causes the operand to be shifted to the right by n
positions.
• operand >> n
– The empty leftmost n bits positions will be filled
with 0’s, if the operand is an unsigned integer.
– Ex unsigned int n1=60;
• Execute the statement n2= n1 >>3;
n1 0000 0000 0011 1100
Shift 1 0000 0000 0001 1110
Shift 2 0000 0000 0000 1111
Shift 3 0000 0000 0000 0111 (==n2)
Ashim Lamichhane 27

28. Bitwise One’s Complement Operator
• Is a unary operator which inverts all the bits
represented by its operand.
• This means that all 0s becomes 1s and 1s
becomes 0s
– If n1=60, then we execute the statement
• n2= ~n1
– The resulting bit pattern represents the decimal:
-61
Ashim Lamichhane 28

29. #include<stdio.h>
voidmain(){
unsigned int n1=60 ,left, right;
left =n1 << 3;
right =n1 >> 3;
printf("%d n", left);
printf("%dn", right);
}
Ashim Lamichhane 29

30. Special Operators
• C supports some special operators and for
now we discuss
– comma operator (,)
– sizeof operator
Ashim Lamichhane 30

31. Comma operator
• The comma operator can be used to link related expressions
together.
• A comma-linked list of expressions are evaluated from left-to-
right and the value of the rightmost expression is the value of
the combined expressions.
• Ex: n3=(n1=50, n2=10,n1+n2)
– The first assign the value 50 to n1
– Assign the value 10 to n2
– Assign sum n1+n2 to n3
Ashim Lamichhane 31

32. sizeof Operator
• Is used with an operand to return the number
of bytes it occupies.
• The operand may be constant, variable or a
data type qualifier.
Ashim Lamichhane 32

33. #include<stdio.h>
Void main(){
unsigned int n1;
printf("Integer Variable =>
%lun",sizeof(n1) );
printf("Double Constant =>
%lun",sizeof(15.11) );
printf("Long int Data type qualifier =>
%lun",sizeof(15L) );
}
Ashim Lamichhane 33

34. Operator precedence and associativity
• The precedence is used to determine how an expression
involving more than one operator is evaluated.
• There are distinct level of precedence.
• The operators at the higher level of precedence are evaluated
first.
• Operators of same precedence are evaluated either from “left
to right” or “right to left” depending on the level also known
as associativity.
Ashim Lamichhane 34

35. Category Operator Associativity
Postfix () [] -> . ++ - - Left to right
Unary + - ! ~ ++ - - (type) * & sizeof Right to left
Multiplicative * /% Left to right
Additive +- Left to right
Shift << >> Left to right
Relational < <= > >= Left to right
Equality == != Left to right
Bitwise AND & Left to right
Bitwise XOR ^ Left to right
Bitwise OR | Left to right
Logical AND && Left to right
Logical OR || Left to right
Conditional ?: Right to left
Assignment = += -= *= /= %= >>= <<= &= ^= |= Right to left
Comma , Left to rightAshim Lamichhane 35

36. • Ex” consider four integer type variable n1=9
n2=12 n3=3 and x
x = n1 –n2 / 3 + n3 *2 -1
Becomes,
x= 9 -12 /3 + 3 * 2 -1
Step1: 9 -12 / 6 * (2-1)
Step2: 9-12/6*1
Step3: 9-2*1
Step4: 9-2
Step5: 7
Ashim Lamichhane 36

37. • Example x=20 and y=5
• If(x==10+15 && y<10)
– Step1: If(x==25 && y<10)
– Step2: if(20==25 && 5 < 10)
– Step3: if(20==25 && TRUE)
– Step3: if(FALSE && TRUE)
• Since one condition is FALSE, the whole condition
is FALSE.
Ashim Lamichhane 37

38. Solve this
• Find the value of “a” in each of the following
statements:
– int i = 3, j = 4, k =8;
– float a = 4.5, b = 6.5, c = 3.5;
• a=b-i/k+c/k
• a = (b-k)/j + (j+c)/k
• a = c - ((i+j)/(k+i)) *b
• a=c-i+j/k+i*b
• a=c+j%2+b
• a=(b+1)%(c+1)
Ashim Lamichhane 38

39. END
Ashim Lamichhane 39