This handout explains loop statements such as for, while, do-while and nested loop in C.

1. C-Programming
Walchand Institute of Technology (RC1131), Solapur Page 1
Handout#5
Assignment/Program Statement:
Write C programs using loop statements such as for, while, do-while and nested
loop.
Learning Objectives:
Students will be able to
- explain decision control statements in C
- draw the flowchart for loop statement solution
- write the algorithm loop statements
- write C code using ‘for’ statement in C
- write C code using ‘while’ statement in C
- write C code using ‘do-while’ ladder in C
- write C code using nested loop in C
Theory:
Programming languages provide various control structures that allow for more
complicated execution paths. A loop statement allows us to execute a statement or
group of statements multiple times. C programming language provides the
following types of loops to handle looping requirements.
- For loop
- While loop
- Do-while loop
- Nested loop
5-a. Write a C program using ‘for’ loop - to display character from A to Z and their
ASCII values
5-b. Write a C program using ‘while’ loop - to print factorial of given number
5-c. Write a C program using ‘do-while’ loop - to find the Fibonacci Series
5-d. Write a C program using nested loop - find the prime numbers from 2 to 100

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Assignment#5a
Assignment/Program Statement:
Write a C program using ‘for’ loop - to display character from A to Z and their
ASCII values
Learning Objectives:
Students will be able to
- write the syntax of ‘for’ loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the ‘for’ loop
Theory:
 A for loop is a repetition control structure that allows you to efficiently
write a loop that needs to execute a specific number of times.
 The syntax of a ‘for’ loop in C programming language is –
for (init; condition; increment)
{
Statement(s);
}
Here is the flow of control in a 'for' loop −
o The init step is executed first, and only once. This step declares and
initializes any loop control variables.
o Next, the condition is evaluated. If it is true, the body of the loop is
executed. If it is false, the body of the loop does not execute and the flow
of control jumps to the next statement just after the 'for' loop.
o After the body of the 'for' loop executes, the flow of control jumps back
up to the increment statement. This statement updates any loop control
variables. This statement can be left blank, as long as a semicolon
appears after the condition.

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o The condition is now evaluated again. If it is true, the loop executes and
the process repeats itself. After the condition becomes false, the 'for' loop
terminates.
Example: C code to print first 10 numbers
for( a = 1; a <= 10; a = a + 1 )
{
printf("value of a: %dn", a);
}
[Reference: http://www.tutorialspoint.com/cprogramming/c_for_loop.htm ]
Flow Diagramfor‘for’loop

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Walchand Institute of Technology (RC1131), Solapur Page 4
Various examples of infinite ‘for’ loop
Loop structure Description
for ( i=1 ; i<=10 ; )
printf("Hello,
World!n");
Here the updating part of the counter variable i is
missing. Hence the value of i will remain 1 forever
and the loop runs infinite times printing Hello,
World!
for ( i=1 ; ; i++ )
printf("Hello,
World!n");
Here the condition part of the loop is missing. Due to
which the loop is forced to run repeatedly infinite
times printing Hello, World! As there isn’t any
condition to terminate.
for ( i=1 ; ; )
printf("Hello,
World!n");
Here the condition as well as updating part is
missing from the loop. Hence it will also iterate
infinite times printing Hello, World!
for ( ; ; )
printf("Hello,
World!n");
Here all the three parts initialization, condition as
well as updation part is missing from the loop.
Hence it will also run infinite times printing Hello,
World!
ASCII Value:
ASCII stands for American Standard Code for Information Interchange.
Computers can only understand numbers, so an ASCII code is the numerical
representation of a character such as 'a' or '@' or an action of some sort.
Below is the ASCII character table for alphabet.
Symbol Decimal Binary
A 65 01000001
B 66 01000010
C 67 01000011
D 68 01000100
Symbol Decimal Binary
a 97 01100001
b 98 01100010
c 99 01100011
d 100 01100100

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E 69 01000101
F 70 01000110
G 71 01000111
H 72 01001000
I 73 01001001
J 74 01001010
K 75 01001011
L 76 01001100
M 77 01001101
N 78 01001110
O 79 01001111
P 80 01010000
Q 81 01010001
R 82 01010010
S 83 01010011
T 84 01010100
U 85 01010101
V 86 01010110
W 87 01010111
X 88 01011000
Y 89 01011001
Z 90 01011010
e 101 01100101
f 102 01100110
g 103 01100111
h 104 01101000
i 105 01101001
j 106 01101010
k 107 01101011
l 108 01101100
m 109 01101101
n 110 01101110
o 111 01101111
p 112 01110000
q 113 01110001
r 114 01110010
s 115 01110011
t 116 01110100
u 117 01110101
v 118 01110110
w 119 01110111
x 120 01111000
y 121 01111001
z 122 01111010

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Flowchart for Problem Statement:
Algorithm:
1. Start
2. i=0
3. If i<26,
print the alphabet and ASCII value
i=i+1
go to step 3
else
go to step 4
4. Stop

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Program:
#include <stdio.h>
#include <conio.h>
int main() {
int i;
for(i = 0; i < 26; i++)
{
printf("%c = %d | %c = %d n",'A'+i,'A'+i,'a'+i,'a'+i);
}
getch();
return 0;
}
Input:
No Input
Output:
A = 65 | a = 97
B = 66 | b = 98
C = 67 | c = 99
D = 68 | d = 100
E = 69 | e = 101
F = 70 | f = 102
G = 71 | g = 103
H = 72 | h = 104
I = 73 | i = 105
J = 74 | j = 106
K = 75 | k = 107
L = 76 | l = 108
M = 77 | m = 109
N = 78 | n = 110
O = 79 | o = 111
P = 80 | p = 112
Q = 81 | q = 113

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R = 82 | r = 114
S = 83 | s = 115
T = 84 | t = 116
U = 85 | u = 117
V = 86 | v = 118
W = 87 | w = 119
X = 88 | x = 120
Y = 89 | y = 121
Z = 90 | z = 122
Practice Problem Statements:
1. Write a C program to calculate the sum of first n natural numbers
2. Write a C program to find factorial of a number
3. Write a C program to print natural numbers
4. Write a C program to print natural numbers in reverse
5. Write a C program to print alphabets
Conclusion:
Thus a C program using ‘for’ loop - to display character from A to Z and their
ASCII values is implemented.
Learning Outcome:
At end of this assignment, students are able to
- write the syntax of ‘for’ loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the ‘for’ loop

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Assignment#5b
Assignment/Program Statement:
Write a C program using ‘while’ loop - to print factorial of given number
Learning Objectives:
Students will be able to
- write the syntax of ‘while’ loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the ‘while’ loop
Theory:
 A while loop in C programming repeatedly executes a target statement as
long as a given condition is true.
 The syntax of a while loop in C programming language is −
while(condition)
{
statement(s);
}
 Here, statement(s) may be a single statement or a block of statements. The
condition may be any expression, and true is any nonzero value. The loop
iterates while the condition is true.
 When the condition becomes false, the program control passes to the line
immediately following the loop.
[Reference: http://www.tutorialspoint.com/cprogramming/c_while_loop.htm ]
Example: C code to print first 10 numbers
a=1;
while ( a <= 20 )
{
printf("value of a: %dn", a);
a++;

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}
Flow Diagram for ‘while’ loop

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Flowchart for Problem Statement:
Algorithm:
1. Start
2. Enter the number whose factorial need to be found
3. f=1
4. i=1
5. If i<=num
f=f*I
i=i+1
go to step 5
else
go to step 6

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6. Display the factorial of the given number
7. Stop
Program:
#include<stdio.h>
int main()
{
int num,f,i;
printf("Enter a number: ");
scanf("%d",&num);
f=1;
i=1;
while(i<=num)
{
f = f * i;
i++;
}
printf("Factorial of %d is: %d",num,f);
return 0;
}
Input:
Enter a number:4
Output:
Factorial of 4 is: 24
Practice Problem Statement:
1. Write a program to print sum of all even numbers between 1 to n.
2. Write a program to print sum of all odd numbers between 1 to n.
3. Write a program to print table of any number.

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4. Write a program to enter any number and calculate sum of all natural
numbers between 1 to n.
5. Write a program to enter any number and calculate sum of its digits.
Conclusion:
Thus a C program using ‘while’ loop - to print factorial of given number is
implemented.
Learning Outcomes:
At end of this assignment, students are able to
- write the syntax of ‘while’ loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the ‘while’ loop
At the end of this assignment, students are able to
- write the syntax of ‘while’ loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the ‘while’ loop

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Walchand Institute of Technology (RC1131), Solapur Page 14
Assignment#5c
Assignment/Program Statement:
Write a C program using ‘do-while’ loop - to find the Fibonacci Series
Learning Objectives:
Students will be able to
- write the syntax of ‘do-while’ loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the ‘do-while’ loop
Theory:
 Unlike for and while loops, which test the loop condition at the top of the
loop, the do...while loop in C programming checks its condition at the
bottom of the loop.
 A do...while loop is similar to a while loop, except the fact that it is
guaranteed to execute at least one time.
 The syntax of a do...while loop in C programming language is –
do {
statement(s);
} while( condition );
 The conditional expression appears at the end of the loop, so the
statement(s) in the loop executes once before the condition is tested.
 If the condition is true, the flow of control jumps back up to do, and the
statement(s) in the loop executes again. This process repeats until the given
condition becomes false.
Example: C code to print first 10 numbers
a=1;
do
{
printf("value of a: %dn", a);

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a++;
} while ( a <=10 )
[Reference: http://www.tutorialspoint.com/cprogramming/c_do_while_loop.htm ]
Flow Diagram for ‘do-while’ loop

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Flowchart for Problem Statement:

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Algorithm:
1. Start
2. First=0, second=1
3. Enter the number of terms in Fibonacci series
4. Display first and second term of Fibonacci series
5. If i<=n
c=first second
Display c
first = second
second = c
i=i+1
go to step 5
else
go to step 6
6. Stop

18. C-Programming
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Program:
#include<stdio.h>
void main()
{
int first, second, c, n, i;
clrscr();
first=0;
second=1;
i=3;
printf("Enter the number of terms: ");
scanf("%d",&n);
printf("%dn%d",first,second);
do
{
c=first+second;
printf("n%d",c);
first = second;
second = c;
i=i+1;
}while (i<=n);
getch();
}
Input:
Enter number of terms: 4
Output:
0 1 2 3
Practice Problem Statement:
1. Write a C program to find power of any number using for loop.
2. Write a C program to enter any number and print all factors of the number.
3. Write a program to display character from A to Z and their ASCII values
4. Write a C program to enter any number and calculate product of its digits.

19. C-Programming
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5. Write a C program to enter any number and print its reverse.
Conclusion:
Thus a C program using ‘do-while’ loop - to find the Fibonacci Series is
implemented.
Learning Objectives:
At the end of this assignment, students are able to
- write the syntax of ‘do-while’ loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the ‘do-while’ loop

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Assignment#5d
Assignment/Program Statement:
Write a C program using nested loop – to find the prime numbers of n-terms
Learning Objectives:
Students will be able to
- write the syntax of nested loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the nested loop
Theory:
 C programming allows you to use one loop inside another loop. The
following section shows a few examples to illustrate the Theory.
 The syntax for a nested for loop statement in C is as follows −
for ( init; condition; increment ) {
for ( init; condition; increment ) {
statement(s);
}
statement(s);
}
Flow Diagram for nested for loop

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 The syntax for a nested while loop statement in C programming language is
as follows −
while(condition) {
while(condition) {
statement(s);
}
statement(s);
}
Flow Diagram for nested while loop

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 The syntax for a nested do...while loop statement in C programming
language is as follows −
do {
statement(s);
do {
statement(s);
}while( condition );
}while( condition );
Flow Diagram for nested do-while loop

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 A final note on loop nesting is that you can put any type of loop inside any
other type of loop. For example, a 'for' loop can be inside a 'while' loop or
vice versa.
[Reference: http://www.tutorialspoint.com/cprogramming/c_nested_loops.htm ]
Flowchart for Problem Statement:

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Algorithm:
1. Start
2. c=0, i=1
3. Read the number n
4. If i <= n
if (n % i == 0)
c++;
end if
i=i+1
go to step 4
else
go to step 5
5. if c = 2
printf("%d is a Prime number",n);
go to step 6
else
printf("%d is not a Prime number",n);
go to step 6
6. Stop

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Program:
#include <stdio.h>
void main() {
int n, i, c = 0;
clrscr();
printf("Enter any number n:");
scanf("%d", &n);
for (i = 1; i <= n; i++)
{
if (n % i == 0)
{
c++;
}
}
if (c == 2) {
printf("%d is a Prime number",n);
}
else {
printf("%d is not a Prime number",n);
}
getch();
}
Input:
Enter any number n: 5
Output:
2 is prime
3 is prime
5 is prime
Practice Problem Statement:
1. Write a program to print all even numbers between 1 to 100.
2. Write a program to print all even numbers between 1 to 100 and sum of it.

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Walchand Institute of Technology (RC1131), Solapur Page 26
3. Write a program to print all odd number between 1 to 100.
4. Write a program to print all odd numbers between 1 to 100 and sum of it.
5. Write a program to find the prime numbers from 2 to 100 and sum of it.
Conclusion:
Thus a C program using nested loop – to find the prime numbers of n-terms is
implemented.
Learning Outcomes:
At the end of this assignment, students are able to
- write the syntax of nested loop
- draw flowchart for loop statement solution
- write the algorithm for loop statement
- write the program using the nested loop