Structured Programming Unit-4-Operators-and-Expression.pptx

Er. Nipun Thapa
Unit 4 : Expression and Operator

4.1. Operator
foundation of any programming
⚫ Operators are
the
language.
⚫ It can define operators as symbols that help us to perform
specific mathematical and logical computations on
operands.
⚫ In other words, we can say that an operator operates the
operands.
⚫ For example, consider the below statement:
⚫c = a + b;
⚫Here, ‘+’ is the operator known as addition operator and ‘a’
and ‘b’ are operands. The addition operator tells the compiler
to add both of the operands ‘a’ and ‘b’.
Nipun Thapa - BIM2ndC - Unit 4
2

4.1. Operator
Operator Classification
a) According to Number of Operands
⚫Unary Operators: Operators that operates or works with
a single operand are unary operators. For example: (++,)
⚫Binary Operators: Operators that operates or works with
two operands are binary operators. For example: (+ , – ,
* , /)
⚫Ternary Operators: The operators which require three
operands to operate are called ternary operators.
E.g. the operator pair “? :” is ternary operator in C.
3

4.1. Operator
a) According to Number of Operands
4

4.1. Operator
b) According to utility and Action
⚫Arithmetic Operator
⚫Relational Operators
⚫Logical Operators
⚫Assignment Operators
⚫Increment and Decrement Operators
⚫Conditional Operators (Ternary Operator)
⚫Bitwise Operators
⚫Special Operators(Comma Operator and size of Operator)
5

4.2.Arithmetic Operators
⚫ These are used to perform arithmetic/mathematical operations
on operands. C supports all the basic arithmetic operators.
⚫ The following table shows all the basic arithmetic operators. Here A=10 and
B=20
6
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

4.2.Arithmetic Operators (Example)
// Working of arithmetic operators
#include <stdio.h>
int main()
{
int a = 9,b = 4,
c;
c = a+b;
printf("a+b = %d n",c);
c = a-b;
printf("a-b = %d n",c);
c = a*b;
printf("a*b = %d
n",c);
c = a/b;
printf("a/b = %d n",c);
c = a%b;
printf("Remainder
when a divided by b =
%d n",c);
return 0;
7

⚫ //LAB 2. Qn.4 : Program to convert days into days and month
#include<stdio.h>
int main()
{
int day,month; printf("Enter
days:"); scanf("%d",&day);
month=day/30; day=day
%30; // reminder
printf("%d Month",month);
printf("n%d Days",day);
return 0;
}
8

⚫ //LAB2.Qn.5:Program that read second and convert into
hour,minute and second.
#include<stdio.h>
int main()
{
int sec,min,hr,rsec;
printf("Enter second:");
scanf("%d",&sec);
hr=sec/3600; rsec=sec
%3600; min=rsec/60;
sec=rsec%60;
printf("n %d hour, %d
minutes, %d
second",hr,min,sec);
return 0;
}
9

⚫ /*LAB2.Q.N.6:Program to sum the digit of a positive integer
which is 3 digit long.e.g. 135 : 1+3+5=9*/
#include<stdio.h>
int main()
{
int n,digit1,digit2,digit3,sum;
printf("Enter 3 digit number:");
scanf("%d",&n);
digit1=n%10;
n=n/10;
digit2=n%10;
n=n/10;
digit3=n%10;
sum=digit1+digit2+digit3;
printf("Sum=%d",sum);
return 0;
}
10

4.3. Relational Operators
⚫A relational operator checks the relationship between
two operands.
⚫If the relation is true,
it returns 1;
⚫if the relation is false,
it returns value 0.
11

== 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.
Assume variable A holds 10 and variable B holds 20 then −
12

// Working of relational operators
#include <stdio.h>
int main()
{ int a = 5, b = 5, c = 10;
printf("%d == %d is %d n", a, b, a == b);
printf("%d == %d is %d n", a, c, a == c);
printf("%d > %d is %d n", a, b, a > b);
printf("%d > %d is %d n", a, c, a > c);
printf("%d < %d is %d n", a, b, a < b);
printf("%d < %d is %d n", a, c, a < c);
printf("%d != %d is %d n", a, b, a != b);
printf("%d != %d is %d n", a, c, a != c);
printf("%d >= %d is %d n", a, b, a >= b);
printf("%d >= %d is %d n", a, c, a >= c);
printf("%d <= %d is %d n", a, b, a <= b);
printf("%d <= %d is %d n", a, c, a <= c);
return 0;
}
13

4.4. Logical Operator
⚫ An expression containing logical operator returns either 0 or 1
depending upon whether expression results true or false.
⚫ Logical operators are commonly used in decision making in C
programming.
14
Operator Meaning Example
&&
Logical AND. True only if all operands are
true
If c = 5 and d = 2 then,
expression ((c==5) &&
(d>5)) equals to 0.
||
Logical OR. True only if either one operand
is true
If c = 5 and d = 2 then,
expression ((c==5) ||
(d>5)) equals to 1.
! Logical NOT. True only if the operand is 0
If c = 5 then, expression
!(c==5) equals to 0.

4.4. Logical Operator (Example)
#include <stdio.h>
int main()
15
{ int a = 5, b = 5, c = 10, result;
result = (a == b) && (c > b);
printf("(a == b) && (c > b) is %d n", result);
result = (a == b) && (c < b);
printf("(a == b) && (c < b) is %d n", result);
result = (a == b) || (c < b);
printf("(a == b) || (c < b) is %d n", result);
result = (a != b) || (c < b);
printf("(a != b) || (c < b) is %d n", result);
result = !(a != b);
printf("!(a != b) is %d n", result);
result = !(a == b);
printf("!(a == b) is %d n", result);
return 0;
}

4.4. Logical Operator
Explanation of logical operator program
⚫(a== b) && (c > 5) evaluates to 1 because
both operands (a==b) and (c > b) is 1 (true).
⚫(a == b) && (c < b) evaluates to 0 because operand (c < b) is
0 (false).
⚫(a == b) || (c < b) evaluates to 1 because (a = b) is 1 (true).
⚫(a != b) || (c < b) evaluates to 0 because both operand (a !=
b) and (c < b) are 0 (false).
⚫!(a != b) evaluates to 1 because operand (a != b) is 0 (false).
Hence, !(a != b) is 1 (true).
⚫!(a == b) evaluates to 0 because (a == b) is 1
(true). Hence, !(a == b) is 0 (false).
16

4.5. Assignment Operators
⚫ Assignment operators are used to assign value to a variable.
⚫ The left side operand of the assignment operator is a variable and
right side operand of the assignment operator is a value.
⚫ The value on the right side must be of the same data-type of variable
on the left side otherwise the compiler will raise an error.
17

4.5. Assignment Operators
= assigns values from right side operands to left side
operand
a=b
+= adds right operand to the left operand and assign the
result to left
a+=b is same as
a=a+b
-= subtracts right operand from the left operand and
assign the result to left operand
a-=b is same as
a=a-b
*= mutiply left operand with the right operand and assign
the result to left operand
a*=b is same as
a=a*b
/= divides left operand with the right operand and assign
the result to left operand
a/=b is same as
a=a/b
%= calculate modulus using two operands and assign the
result to left operand
a%=b is same as
a=a%b
18

4.6. Increment and Decrement Operator
⚫ Increment:
⚫ The ‘++’ operator is used to increment the value of an integer.
⚫ When placed before the variable name (also called pre-increment
operator), its value is incremented instantly. For example, ++x.
⚫ And when it is placed after the variable name (also called post-
increment operator), its value is preserved temporarily
until the execution of this statement and it gets
updated before the execution of the next statement. For
example, x++.
⚫ Decrement:
⚫ The ‘ – – ‘ operator is used to decrement the value of an integer.
⚫ When placed before the variable name (also called pre-decrement
operator), its value is decremented instantly. For example, – – x.
⚫ And when it is placed after the variable name (also called post-
decrement operator), its value is preserved temporarily
until the execution of this statement and it gets
updated before the execution of the next statement. For
example, x – –.
19

#include <stdio.h>
int main()
{ int a = 10, b = 4, res;
res = a++;
printf("a is %d and res is %dn", a, res);
res = a--;
printf("a is %d and res is %dn", a, res
res = ++a;
res = --a;
return 0;
}
20
4.6. Increment and Decrement Operator (Example)

4.7. Conditional Operator
⚫The conditional operators in C language are known by
two more names
1. Ternary Operator
2. ? : Operator
⚫It is actually the if condition that we use in C language
decision making, but using conditional operator,
we turn the if condition statement into a
short and simple operator.
21

4.7. Conditional Operator
The syntax of a conditional operator is :
expression 1 ? expression 2: expression 3
Explanation:
⚫ The question mark "?" in the syntax represents the if part.
⚫ The first expression (expression 1) generally returns either true
or false, based on which it is decided whether (expression 2) will
be executed or (expression 3)
⚫ If (expression 1) returns true then the expression on the left side
of " : " i.e (expression 2) is executed.
⚫ If (expression 1) returns false then the expression on the right
side of " : " i.e (expression 3) is executed.
22

4.7. Conditional Operator(Example)
#include <stdio.h>
int main()
{
int mark;
printf("Enter mark: ");
scanf("%d", &mark);
puts(mark >= 40 ? "Passed" : "Failed");
return 0;
}
23

/*Lab2 QN11 Program to to find larger value using
conditional operator */
#include<stdio.h>
int main()
{
int n1,n2,larger,smaller;
printf("Enter two number:");
scanf("%d%d",&n1,&n2); // 6 8
larger=n1>n2 ? n1 : n2; // 6>8
printf("The lager is %d",larger);
return 0;
}
24

/*lab 2 QN 12. Program to find largest number
among three integer value using conditional operator.*/
#include<stdio.h>
int main()
{
int n1,n2,n3,large1,large2;
printf("Enter three number:");
scanf("%d%d%d",&n1,&n2,&n3); //2 1 4
large1=n1>n2?n1:n2; // large1= 2
large2=large1>n3?large1:n3; // large2=4
printf("The largest value is %d",large2);
return 0;
}
25

4.8. Bitwise Operators
⚫ The Bitwise operators is used to perform bit-level operations on the
operands.
⚫ The operators are first converted to bit-level and then the calculation
is performed on the operands.
⚫ The mathematical operations such as addition,
subtraction,
multiplication etc. can be performed at bit-level for faster processing.
⚫ For example, the bitwise AND represented as & operator in C or
C++ takes two numbers as operands and does AND on every bit of two
numbers.
⚫ The result of AND is 1 only if both bits are 1
26

4.8. Bitwise Operators
Operators Meaning of operators
& Bitwise AND
| Bitwise OR
^ Bitwise exclusive OR
~ Bitwise complement
<< Shift left
>> Shift right
27

4.8. Bitwise Operators (Example)
#include<stdio.h>
int main()
{
int num1=178;
int num2=63;
int and, or, xor;
and= num1 & num2;
or= num1 | num2;
xor=num1 ^ num2;
printf(“and= %dn”,and);
printf(“or= %dn”,or);
printf(“xor=%dn”,xor);
return 0;
}
Explain (AND)
1011 0010 : (178)
& 0011 1111 : (63)
= 0011 0010 : (50)
OR
1011 0010 :
(178)
| 0011 1111 : (63)
= 1011 1111 :
(190)
XOR
1011 0010 :
(178)
^ 0011 1111 : (63)
= 1000 1101 :
28

4.9. Comma Operator
⚫ The comma operator (represented by the token ,) is a binary operator
that evaluates its first operand and discards the result, it then
evaluates the second operand and returns this value (and type).
⚫ The comma operator has the lowest precedence of any C operator.
⚫ Comma acts as both operator and separator
29

4.9. Comma Operator
1) Comma as an operator:
⚫ The comma operator (represented by the token, ) is a binary operator that
evaluates its first operand and discards the result, it then evaluates the second
operand and returns this value (and type). The comma operator has the
lowest precedence of any C operator, and acts as a sequence point.
/* comma as an operator */
30
int i = (5, 10);
int j = (f1(), f2());
/* 10 is assigned to i*/
/* f1() is called (evaluated) first followed by f2().
The returned value of f2() is assigned to j */
2) Comma as a separator:
⚫ Comma acts as a separator when used with function calls and definitions,
function like macros, variable declarations, enum declarations, and similar
constructs.
/* comma as a separator */
int a = 1, b = 2;
void fun(x, y);

4.9. Comma Operator
3) Comma operator in place of a semicolon.
⚫ We know that in C and C++, every statement is terminated
with a semicolon but comma operator also used to
terminate the statement after satisfying the following
rules.
⚫ The variable declaration statements must be terminated
with
semicolon.
⚫ The statements after declaration statement can be terminated by
comma operator.
⚫ The last statement of the program must be
terminated by
semicolon.
31

4.10. The size of Operator
⚫ sizeof is a much used in the C/C++ programming language.
⚫ It is a compile time unary operator which can be used to compute the size of
its operand.
⚫ The result of sizeof is of unsigned integral type which is usually denoted by
size_t.
⚫ Basically, sizeof operator is used to compute the size of the variable.
Example :
#include <stdio.h>
int main()
{
printf("%lun", sizeof(char));
printf("%lun", sizeof(int));
printf("%lun", sizeof(float));
printf("%lu", sizeof(double));
return 0;
}
32

4.11.Precedence and Associativity of
Operators
⚫ Operator precedence: It dictates the order of evaluation of
operators in an expression.
⚫ Associativity: It defines the order in which operators of the
same precedence are evaluated in an expression.
Associativity can be either from left to right or right to left.
example:
⚫24 + 5 * 4
⚫Here we have two operators + and *, Which operation do you
think will be evaluated first, addition or multiplication? If the
addition is applied first then answer will be 116 and if the
multiplication is applied first answer will be 44. To answer
such question we need to consult the operator precedence
table.
33

Operators
Precedence level
34
1
2
3
4
5
6

Operators
7
8
9
10
11
12
13
14
35
15

Operators
⚫ From the precedence table, we can conclude that the * operator is above
the + operator, so the * operator has higher precedence than the + operator,
therefore in the expression 24 + 5 * 4, subexpression 5 * 4 will be evaluated
first.
36

Operators
⚫34 + 12/4 - 45
37

Operators
⚫12 + 3 - 4 / 2 < 3 + 1
38

N= 2*3/4+4/4+8-2+5/8 where N is integer
Operator : seen
N= 2*3/4+4/4+8-2+5/8 = 6/4+4/4+8-
2+5/8 N= 6/4+4/4+8-2+5/8 = 1+4/4+8-
2+5/8
N= 1+4/4+8-2+5/8 = 1+1+8-2+5/8
N= 1+1+8-2+5/8=1+1+8-2+0
N=1+1+8-2 = 2+8-2
N=2+8-2=10-2
N=8
39

Type Conversion in Expressions
⚫ The type conversion process in C is basically
converting
one type of data type to other to perform some operation.
⚫ The conversion is done only between those datatypes
wherein the conversion is possible ex – char to int and vice
versa.
⚫ It can classify in two group
1. Implicit Type Conversion(Automatic Type Conversion)
2. Explicit Type Conversion(Type cast)
40

⚫ This type of conversion is usually performed by the
compiler when necessary without any commands by the
user. Thus it is also called "Automatic Type Conversion".
⚫ The compiler usually performs this type of conversion
when a particular expression contains more than one data
type. In such cases either type promotion or demotion
takes place.
41

Rules...
1. char or short type operands will be converted to int during an operation
and the outcome data type will also be int.
2. If an operand of type long double is present in the expression, then the
corresponding operand will also be converted to long double same for
the double data type.
3. If an operand of float type is present then the corresponding operand in
the expression will also be converted to float type and the final result
will also be float type.
4. If an operand of unsigned long int is present then the other operand will
be converted to unsigned long int and the final result will also
be unsigned long int.
5. If an operand of long int is present then the other operand will be
converted to long int and the final result will also be long int.
6. If an operand of unsigned int is present then the other operand will be
converted to unsigned int and the final result will also be unsigned int.
42

Example 1
int a = 20;
double b = 20.5;
a + b;
Here, first operand is int type and other is of type double. So, as per rule
2, the variable a will be converted to double. Therefore, the final answer
is double a + b = 40.500000.
43

Example 2
char ch='a';
int a =13;
a + c;
Here, first operand is char type and other is of type int. So, as per rule
1, the char variable will be converted to int type during the operation
and the final answer will be of type int.
We know the ASCII value for ch is 97. Therefore, final answer is
a + c = 97 + 13 = 110.
44

Example 3
char ch='A';
unsigned int a =60;
a * b;
Here, the first operand is char type and the other is of type unsigned int.
So, as per rule 6, char data type will be converted to unsigned int during
the operation. Therefore, the final result will be an unsigned
int variable, 65 + 60 = 125.
45

For ease of understanding follow the flowchart given below, in which
datatypes have been arranged in a hierarchy of highest to the lowest
rank.
46

// An example of implicit conversion
#include<stdio.h>
int main()
{
int x = 10; // integer x
char y = 'a'; // character c
// y implicitly converted to int.
ASCII
// value of 'a' is 97
x = x + y;
// x is implicitly converted to float
float z = x + 1.0;
printf("x = %d, z = %f", x, z);
return 0;
47
} Output:
x = 107, z = 108.000000

2) Explicit Type Conversion
⚫ Explicit type conversion rules out the use of compiler for converting one data type
to another instead the user explicitly defines within the program the datatype of
the operands in the expression.
⚫ The example below illustrates how explicit conversion is done by the user.
Example:
double da = 4.5;
double db = 4.6;
double dc = 4.9;
//explicitly defined by user
int result = (int)da + (int)db + (int)dc;
printf("result = %d", result);
Output
result = 12
48

49

⚫ Thus, in the above example we find that the output result
is 12 because in the result expression the user has
explicitly defined the operands (variables) as integer data
type. Hence, there is no implicit conversion of data type by
the compiler.
⚫ If in case implicit conversion was used the result would be
13.
50

// C program to demonstrate explicit type casting
#include<stdio.h>
int main()
{
double x = 1.2;
// Explicit conversion from double to int
int sum = (int)x + 1;
printf("sum = %d", sum);
return 0;
}
O
u
t
p
u
51

Advantages of Type Conversion
⚫ This is done to take advantage of certain features of type
hierarchies or type representations.
⚫ It helps us to compute expressions containing variables of
different data types.
52

Finished
Unit 4
53

Structured Programming Unit-4-Operators-and-Expression.pptx

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