eln

1. Module – 2
Operators, Decision Control and
Looping Statements

2. Operators
 Arithmetic Operators
 Logical Operators
 Bitwise Operators
 Ternary Operators

3. Some more Arithmetic Operators
 Prefix Increment : ++a
example: int a=5;
b=++a; // value of b=6; a=6;
 Postfix Increment: a++
example: int a=5;
b=a++; // value of b=5; a=6;

4. Continued…
 Modulus (remainder): %
example:
12%5 = 2;
 Assignment by addition: +=
example:
int a=4;
a+=1; //(means a=a+1) value of a becomes 5
Can use -, /, *, % also

5. Continued…
 Comparison (Relational ) Operators:
<, > , <=, >= , !=, ==
 Logical Operators: !, &&, ||
example:
int a=4, b=5;
a<b returns a true(non zero number) value.
 Bitwise Operators: <<, >>, ~, &, | ,^ .
example:
int a=8;
a= a>>1; // value of a becomes 4

6. 6
Logical Operators

7. i) 3 + 4*5 - 6/3*4/8 + 2*6 - 4*3*2
ii) -1.5+2.0*3.5-5.0/2.5+1.25

8. Truth Table For Bit Wise Operation
& – Bitwise AND
| – Bitwise OR
~ – Bitwise NOT
^ – XOR
<< – Left Shift
>> – Right Shift

9. Operator Precedence
 Meaning of a + b * c ?
is it a+(b*c) or (a+b)*c ?
 All operators have precedence over each other
 *, / have more precedence over +, - .
If both *, / are used, associativity comes into picture. (more on this later)
example : 5+4*3 = 5+12= 17.

10. Conditional Or Ternary Operators
 Conditional operators return one value if condition is true and returns
another value is condition is false.
 This operator is also called as ternary operator.
Syntax : (Condition? true_value: false_value);
Example : (A > 100 ? 0 : 1);

11. Precedence Table
Highest on top
++ -- (Postfix)
++ -- (Prefix)
* / %
+ -
<< >>
< >
&
|
&&
||

12. 8 0 6 12
Evaluate Arithmetic Expression
x = 2 * 3 / 4 + 4 / 4 + 8 - 2 + 5 / 8;
a = 7 / 22 * ( 3.14 + 2 ) * 3 / 5 ;
b = 4 + 2 % - 8 ;
c = ( 10 * 2 ) ( 3 + ( 2.5 + 6 ) ( 4 + 18 ) ;

13. 13
Data types and their sizes

14. 14
Data types and their sizes

15. 15

16. 16
Operation Result Operation Result
5 / 2 2 2 / 5 0
5.0 / 2 2.5 2.0 / 5 0.4
5 / 2.0 2.5 2 / 5.0 0.4
5.0 / 2.0 2.5 2.0 / 5.0 0.4
Integer and float conversion

17. 17
Integer and float conversion
k is integer variable and a is a real variable

18. ASCII Codes
18

19. 19

20. 20
#include <stdio.h>
int main()
{
char c;
printf("Enter a character: ");
// Reads character input from the user
scanf("%c", &c);
// %d displays the integer value of a character
// %c displays the actual character
printf("ASCII value of %c = %d", c, c);
return 0;
}
Print ASCII Value

21. Output ?
#include<stdio.h>
void main( )
{
int a, b ;
a = -4 - - 4 ;
b = -4 - - ( - 4 ) ;
printf ( "a = %d b = %d", a, b ) ;
}

22. Type Conversion
 Converting the value of one data type (int, float, double, etc.) to
another data type.
 This process is known as type conversion.

23. C Example
#include <stdio.h>
int main()
{
int number = 34.78;
printf("%d", number);
return 0;
}
// Output: 34

24.  There are two types of type conversion:
Implicit Conversion
Explicit Conversion
 In implicit type conversion, the value of one type is automatically
converted to the value of another type.
 In explicit type conversion, we manually convert values of one
data type to another type.

25. Implicit type conversion example
#include<stdio.h>
int main ( )
{
// character variable
char alphabet = 'a';
printf("Character Value: %cn", alphabet);
// assign character value to integer variable
int number = alphabet;
printf("Integer Value: %d", number);
return 0;
}

26. Explicit type conversion example
#include<stdio.h>
int main() {
// create an integer variable
int number = 35;
printf("Integer Value: %dn", number);
// explicit type conversion
double value = (double) number;
printf("Double Value: %.2lf", value);
return 0;
}

27. C –Type Casting
 Converting one datatype into another is known as type casting
or, type-conversion. For example, if you want to store a 'long'
value into a simple integer then you can type cast 'long' to 'int’.
 You can convert the values from one type to another explicitly
using the cast operator as follows − (type_name) expression

28. C Program for floating-point operation
#include <stdio.h>
main ( )
{
int sum = 17, count = 5;
double mean;
mean = (double) sum / count;
printf("Value of mean : %fn", mean );
}

29.  Integer promotion is the process by which values of integer type "smaller"
than int or unsigned int are converted either to int or unsigned int.
Usual Arithmetic Conversion
 The usual arithmetic conversions are implicitly performed to cast their
values to a common type. The compiler first performs integer promotion; if
the operands still have different types, then they are converted to the type
that appears highest in the following hierarchy −

31. //C Program of adding a character with an integer
#include <stdio.h>
main() {
int i = 17;
char c = 'c'; /* ascii value is 99 */
int sum;
sum = i + c;
printf("Value of sum : %dn", sum );
}

32. Control Statements or Flow Control
 Sequence Control Statements
 Decision Control Statements
 Loop Control Statements
 Case Control Statements

33. Decision Control Statements
Perform different set of actions based on the situation.
1. if
2. if else
3. switch

34. The if statement
if ( this condition is true )
execute this statement ;
if ( this condition is true )
{
execute this block;
}

35. The if statement
if ( this condition is true )
execute this statement ;
if ( this condition is true )
{
execute this block;
}

36. 36
void main ( )
{
int n ;
printf ( "Enter a number n" ) ;
scanf ( "%d", &n ) ;
if ( n < =100 )
printf ( “The number is less than or equal to 100" ) ;
}
The if statement example

37. The if-else statement
if ( this condition is true )
execute this statement ;
else
execute this statement ;
if ( this condition is true )
{
execute this block;
}
else
{
execute this block;
}

38. 38
void main( )
{
int n ;
printf ( "Enter a number n" ) ;
scanf ( "%d", &n ) ;
if ( n <= 100 )
printf ( “The number is less than or equal to 100" ) ;
else
printf ( “The number is greater than 100" ) ;
}
The if-else example

39. The if-else statement
if ( this condition is true )
execute this statement ;
else
execute this statement ;
if ( this condition is true )
{
execute this block;
}
else
{
execute this block;
}

40. The else-if statement
if ( expression )
execute this statement ;
else if ( expression )
execute this statement ;
else if ( expression )
execute this statement ;
else if ( expression )
execute this statement ;
else
execute this statement ;
Multi-way
decision
Note:
Last else is
optional

41. Nesting of if-else statements
if (expression1)
{
// code to be executed
if (expression2)
{
// code to be executed
// if condition2 is true
}
}

42. Switch case statements
switch( expression )
{
case value-1: Block-1;
break;
case value-2: Block-2;
break;
…………………
case value-n: Block-n;
break;
default:
Block-1;
break;
}
Statement-x; Note: default is optional
expression can
be integral or
character

43. 43
#include <stdio.h>
int main()
{
int x;
printf (“Enter your choice”);
scanf (“%d”,&x);
switch (x)
{
case 1: printf("Choice is 1");
break;
case 2: printf("Choice is 2");
break;
case 3: printf("Choice is 3");
break;
default: printf("Choice other than 1, 2 and 3");
break;
}
return 0;
}
Switch case example

44. 44
switch ( marks / 10 )
{
case 4 :
case 5 : grade = ‘D’; break;
case 6 :
case 7 : grade = ‘C’; break;
case 8 :
case 9 : grade = ‘B’; break;
case 10 : grade = ‘A’; break;
default : grade = ‘F’; break;
}
Switch case example

45. Difference between if-else and switch
 “If-else” can evaluate float conditions, “switch” cannot.
 “If-else” can evaluate relational operators, “switch” cannot.

46. Switch Examples
 Write a C program to print day of week name using switch case.
 Write a C program to print number of days in a month using
switch case.
 Write a C program to find maximum between two numbers using
switch case.
 C program to check positive negative or zero using switch case.

47. 47
int main ( )
{
int num;
printf("Enter any number: ");
scanf("%d", &num);
switch (num > 0)
{ // Num is positive
case 1: printf("%d is positive.", num); break; // Num is either negative
or zero
case 0: switch (num < 0)
{
case 1: printf("%d is negative.", num);
break;
case 0: printf("%d is zero.", num); break; }
break;
}
return 0;
}
Program to check positive or negative or zero using switch

48. Example program
 A commercial bank has introduced an incentive of giving bonus to all
its deposit holders. The policy is as follows: A bonus of 2 percent of the
balance held is given to every one and 5 percent is given to female
account holders if their balance is more than Rs.5000.
 Note: Take gender using character variable. Example M means male
and F means female.
 Inputs : Balance amount and the gender
 Output: bonus and balance after adding bonus

49. The else-if statement
if ( expression )
execute this statement ;
else if ( expression )
execute this statement ;
else if ( expression )
execute this statement ;
else if ( expression )
execute this statement ;
else
execute this statement ;
Multi-way
decision
Note: Last else is
optional

50. 50
The else-if flowchart

51. Example Program
 Write a C program to input marks of five subjects Physics,
Chemistry, Biology, Mathematics and Computer. Calculate
percentage and grade according to following:
Percentage >= 90% : Grade A
Percentage >= 80% : Grade B
Percentage >= 70% : Grade C
Percentage >= 60% : Grade D
Percentage >= 40% : Grade E
Percentage < 40% : Grade F

52. 52
switch ( avg_marks / 10 )
{
case 0 :
case 1 :
case 2 :
case 3 : grade = ‘F’; break;
case 4 :
case 5 : grade = ‘E’; break;
case 6 : grade = ‘D’; break;
case 7 : grade = ‘C’; break;
case 8 : grade = ‘B’; break;
case 9 :
case 10 : grade = ‘A’; break;
default : grade = ‘F’; break;
}
Switch case example

53. The ? : operator
 Ternary operator is used for decision making in place of conditional
statements if and else.
 Takes three arguments.
conditional_expression ? value_if_true : value_if_false
int a = 10, b = 20, c;
if (a < b)
{ c = a;
}
else
{ c = b;
}
printf("%d", c);
int a = 10, b = 20, c;
c = (a < b) ? a : b;
printf("%d", c);

54. Example Program
Consider the weekly salary of a sales guy who is selling some products. If x
is the number of products sold in a week, his weekly salary is given by
4x+100 for x<40
Salary = 300 for x=40
4.5x+150 for x>40

55. Iterative statements

56. Loops in C
A sequence of statements are executed until some conditions for
termination is satisfied.
Two parts:
1. Body of
the loop
2. Control
statement

57. Looping process steps
1. Setting and initialization of the condition variable
2. Execution of the statements in loop
3. Test for a specified value of the condition variable for execution of
the loop
4. Incrementing or updating the condition variable

58. Three types of loops
 The while statement
 The do-while statement
 The for statement

59. The while statement
 Entry controlled loop statement
 The test condition is evaluated and if the condition is true, then the body of
the loop is executed.
while (test condition)
{
// statements inside the body of the loop
}

60. Print numbers from 1 to 5
60
#include <stdio.h>
int main()
{
int i = 1; // Initialization
while (i <= 5) // Testing
{
printf("%dn", i);
i++; // Incrementing
}
return 0;
}

61. While examples
 Write a C program to find the sum of all integers between 1 and 10.
 Write a C program to find the sum of squares of all integers between 1
and 10.
 Write a program to evaluate the equation y=xn where n is a non
negative integer.

62. The do while statement
 Exit controlled loop statement.
 The body of the loop is executed first.
 At the end of the loop, the test condition is evaluated.
do
{
// statements inside the body of the loop
}
while (test condition);

63. Program to add numbers until the user enters zero
63
#include <stdio.h>
void main()
{
double number, sum = 0;
// the body of the loop is executed at least once
do
{
printf("Enter a number: ");
scanf("%lf", &number);
sum += number;
}
while(number != 0.0);
printf("Sum = %.2lf",sum);
}

64. The for statement
Entry controlled loop, more concise loop control structure.
1. Initialization of the control variables is done first. Ex: i=0, count=0 (loop
control variables)
2. The value of the control variable is tested using the test condition. Ex:
i<10
3. When the body of the loop is executed, control is transferred back to for
statement. The control variable is incremented/updated using an
assignment statement. Ex: i=i+1
for (initialization; test_condition ; increment)
{
// statements inside the body of loop
}

65. Flow chart of for statement
65

66. Print numbers from 0 to 10
#include <stdio.h>
int main()
{
int i;
for (i = 0; i <= 10; ++i)
{
printf("%d ", i);
}
return 0;
}

67. For loop examples
 Write a C program to find the sum of all integers between 1 and 10.
 Write a C program to find the sum of squares of all integers between 1
and 10.
 Write a program to evaluate the equation y=xn where n is a non
negative integer.
 Write a program to find the factorial of a number.
 Write a program to find the gcd of two numbers.
 Write a program to print first 10 multiples of 5.
 C program to add digits of a number:

68. Loop Control Statements
Loop control statements change execution from its normal
sequence.
Control Statement & Description
break statement
Terminates the loop or switch statement and transfers execution to the
statement immediately following the loop or switch.
continue statement
Causes the loop to skip the remainder of its body and immediately
retest its condition prior to reiterating.
goto statement
Transfers control to the labeled statement.

69. 69
break statement

70. 70
// Program to calculate the sum of a maximum of 10 numbers
// If a negative number is entered, the loop terminates
void main()
{
int i;
double number, sum = 0.0;
for(i=1; i <= 10; ++i)
{
printf("Enter a n%d: ",i);
scanf("%lf",&number);
// If the user enters a negative number, the loop ends
if(number < 0.0)
{
break;
}
sum += number; // sum = sum + number;
}
printf("Sum = %.2lf",sum);
}

71. 71
continue statement

72. 72
// Program to calculate the sum of a maximum of 10 numbers
// Negative numbers are skipped from the calculation
void main()
{
int i;
double number, sum = 0.0;
for(i=1; i <= 10; ++i)
{
printf("Enter a n %d: ",i);
scanf("%lf",&number);
if(number < 0.0)
{
continue;
}
sum += number; // sum = sum + number;
}
printf("Sum = %.2lf",sum);
}

73. 73
break continue
A break can appear in both switch and loop
(for, while, do) statements.
A continue can appear only in loop
(for, while, do) statements.
A break causes the switch or loop statements
to terminate the moment it is executed. Loop
or switch ends abruptly when break is
encountered.
A continue doesn't terminate the loop, it
causes the loop to go to the next iteration. All
iterations of the loop are executed even
if continue is encountered.
The continue statement is used to skip
statements in the loop that appear after
the continue.
The break statement can be used in
both switch and loop statements.
The continue statement can appear only in
loops. You will get an error if this appears in
switch statement.
When a break statement is encountered, it
terminates the block and gets the control out
of the switch or loop.
When a continue statement is encountered, it
gets the control to the next iteration of the
loop.
A break causes the innermost enclosing loop
or switch to be exited immediately.
A continue inside a loop nested within
a switch causes the next loop iteration.

74. Infinite Loop
 A loop becomes an infinite loop if a condition never becomes false.
 The for or while loop is traditionally used.
 Most of the time we create infinite loops by mistake.
 Commonly used in programs that keep running for long periods of time
until they are stopped.0
#include <stdio.h>
int main ()
{
for( ; ; ) // or while(1)
{
printf("This loop will run forever.n");
}
return 0;
}

75. 75
Infinite Loop mistakes

76. 76
int choice;
while(1)
{
printf(“1.Create databasen”);
printf(“2.Insert new recordn”);
printf(“3.Modify a recordn”);
printf(“4.Delete a recordn”);
printf(“5.Display all recordsn”);
printf(“6.Exitn”);
printf(“Enter your choice : “);
scanf(“%d”,&choice);
switch(choice)
{
case 1: printf(“Database created…..nn”); break;
case 2:printf(“Record inserted…..nn”);break;
case 3:printf(“Record modified…..nn”);break;
case 4:printf(“Record deleted…..nn”);break;
case 5:printf(“Records displayed…..nn”);break;
case 6:exit(1);
default:printf(“Wrong choicen”);
}
}
Infinite Loop example

77. Programming Examples
 Given a number n, print triangular pattern. We are allowed to
use only one loop.

78. Programming Examples
• Given a positive integer n. Print the inverted
triangular pattern.

79. Roots of a quadratic equation
 a, b and c are known values. a can't be 0.
 "x" is the variable or unknown.

80. Discriminant
 b2 − 4ac in the formula is called the Discriminant, because it can
"discriminate" between the possible types of answer:
 when b2 − 4ac is
 positive, we get two Real solutions
 Zero, we get just ONE real solution (both answers are the same)
 Negative, we get a pair of Complex solutions
 Ex: 5x2 + 6x + 1 = 0, Solution x = −0.2 or −1

81. Algorithm: Quadratic Equation
81
Step 1: Start
Step 2: Read the values of non-zero coefficients a,b and c.
Step 3: Compute the value of discriminant (disc) which is equal to (b*b-4*a*c).
Step 4: Check if disc is equal to 0. If true, then go toStep 5. Otherwise, go to Step 6
Step 5: Compute the roots.
root1 = (-b)/ (2*a) , root2=root1
Output the values of roots, root1 and root2. Go to Step 9.
Step 6: Check if disc is greater than zero or not. If true, then go to Step 7.Otherwise,
go to Step 8.
Step 7: Compute the real and distinct roots, root1 = (-b+sqrt(disc))/(2*a)
root2 = (-b-
sqrt(disc))/(2*a)
Output the values of roots, root1 and root2. Go to Step 9.
Step 8: Compute the complex and distinct roots.
Compute the real part, r_part = (-b)/(2*a)
Compute the imaginary part, i_part = sqrt(-disc)/(2*a)
Output roots as root1 = r_part + i_part
root2 = r_part – i_part
Step 9: Stop

82. 82

83. Palindrome
int main()
{
int num,rev=0,rem,temp;
printf("Enter a number : ");
scanf("%d",&num);
temp = num;
while(num != 0)
{
rem=num%10;
rev= rev*10+rem;
num = num / 10;
}
printf("n The reverse of given number is %d ",rev);
if(temp==rev)
printf("n The given number %d is a Palindrome",temp);
else
printf("n The given number %d is not a Palindrome",temp);
}

84. Binomial coefficient
 The binomial theorem describes the algebraic expansion of powers of
a binomial.
 According to the theorem, it is possible to expand the
polynomial (x + y)n into a sum involving terms of the form axbyc
 where the exponents b and c are nonnegative integers with b + c = n,
and
 the coefficient a of each term is a specific positive integer depending
on n and b.
 The coefficient a in the term of axbyc is known as the binomial
coefficient.
 These coefficients for varying n and b can be arranged to form Pascal's
triangle.
 For example (for n = 4)

85. Binomial coefficient
85

86. 86
Pascal’s Triangle

87. Pascal’s Triangle
87

88. The goto statement
 To branch unconditionally from one point to another in the program.
 Requires a label in order to identify the place where the branch is to be
made.
 A label is any valid variable name followed by a colon.
goto label;
-----
-----
label:
statement;
label:
statement;
-----
-----
goto label;

89. Example Program
main()
{
double a,b;
read:
printf(“Enter a number greater than 0n”);
scanf(“%f”,&a);
if(a<0)goto read;
b= sqrt(a);
printf(“square root=%f”,b);
}

90. Thank you