Arithmetic operator, Relational operator, Logical or Boolean operator, Assignment, Operator, Ternary operator, Bitwise operator, Increment or Decrement operator, Comma operator. https://github.com/ashim888/csit-c

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.
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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
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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)
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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
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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
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7. Integer Arithmetic
• Division Rule
– Int / int =int
– Float / float= float
– Int / float = float
– Float /int =float
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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 );
}
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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.
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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" );
}
}
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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.
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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" );
}
}
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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
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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
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15. void main(){
int a= 10;
clrscr();
printf("a =%d",a);
printf("a =%d",++a);
printf("a =%d",a++);
printf("a =%d",a);
}
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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
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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
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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();
}
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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
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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 (^)
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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
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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
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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
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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 );
}
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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 ( >> )
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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)
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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)
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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
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29. #include<stdio.h>
voidmain(){
unsigned int n1=60 ,left, right;
left =n1 << 3;
right =n1 >> 3;
printf("%d n", left);
printf("%dn", right);
}
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30. Special Operators
• C supports some special operators and for
now we discuss
– comma operator (,)
– sizeof operator
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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
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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.
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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) );
}
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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.
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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
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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
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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.
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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)
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39. END
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