SEBA
COMPUTER
SCIENCE
CHAPTER-4
INTRODUCTION TO LOOPS
1. Why we Use a loop in a C program?
We use a loop in C program because
it enables to alter the flow of the program so that instead of writing the same
code again and again, we can execute the same code for a finite number of
times.
OR(
YOU CAN ALSO WRITE)
We use a loop in a C program
because it allows us to execute a statement or group of statements multiple times.
2. Do we need to use only one type of loop in a C program? Justify your answer by writing a C program.
No we need not only use one type of loop in C program, we can use one or more loops inside any other like while, for or do…while loop. For example if we want to display I read in Class X 5 time we can write the program using while or for loop also.
Example-a): Using while loop
Example-b): Using do-while loop|
a) 12 + 22 + 32 + 42
+……. + N2 #include <stdio.h> int main() { int i,
n, sum =0;
printf("Enter the value of N: \n");
scanf("%d", &n); for
(i=1; i<=n; i++) { sum
= sum + (i*i); }
printf("Sum=%d", sum); return
0; }
|
b) 13+ 23 + 33+ 43 +…….
+ N3 #include
<stdio.h> int main() { int i,
n, sum =0;
printf("Enter the value of N: \n");
scanf("%d", &n); for
(i=1; i<=n; i++) { sum
= sum + (i*i*i); }
printf("Sum=%d", sum); return
0; }
|
3.
What will happen if we write a while loop with 1 in place of the condition? Try
it in a simple C program. Hint
While(1)
{
Printf(“ We must raise our voice
against corruption\n);
}
If we write a while loop with 1 in
place of condition, a loop becomes an infinite loop as a result endless loop if
a condition never becomes false.
4. Name the different portion of a for loop. Can we put more than one statement within a portion?
The different portion of a loop
are:
Initialization
statement: describes the starting point of the loop, where we initialize
one or mor counter variable
Condition
or Test statement: It is a place where we write conditional expression,
which determine whether the body of the loop is executed or terminated.
Update
statements(Increment / decrement): It is a place where we increment or
decrement initialized counter variable.
Yes, We can put more than one
statement within a portion:
For
example:
|
#include<stdio.h> int x,y for (x=0, y=10; x<5, y<6; x++, y--) { Statements; } |
5. Answer with True or False
1. If the condition of the while
loop is false, the control comes to the second statement inside the loop. FALSE
2.We can use at most three loops
in a single C program FALSE
3. The statements inside the
do-while loop executes at least once even if the condition is false. TRUE
4. Only the first statement inside
the do-while loop executes when the condition is false. FALSE
5. In a do-while loop, the
condition is written at the end of the loop. TRUE
6. Programing Excercises:
A.
Write a C program to find the summation of the following
a) 12 + 22 + 32
+ 42 +……. + N2
b) 13+ 23 + 33+
43 +……. + N3
c) 1*2 + 2*3 + 3*+3*4 +…N*(N+1)
|
a) 12 + 22 + 32 + 42
+……. + N2 #include <stdio.h> int main() { int i,
n, sum =0;
printf("Enter the value of N: \n");
scanf("%d", &n); for
(i=1; i<=n; i++) { sum
= sum + (i*i); }
printf("Sum=%d", sum); return
0; } |
b) 13+ 23 + 33+ 43 +…….
+ N3 #include
<stdio.h> int main() { int i,
n, sum =0;
printf("Enter the value of N: \n");
scanf("%d", &n); for
(i=1; i<=n; i++) { sum
= sum + (i*i*i); }
printf("Sum=%d", sum); return
0; } |
|
c) 1*2 + 2*3 + 3*+3*4 +…N*(N+1) #include
<stdio.h> int main() { int i,
n, sum =0; printf("Enter
the value of N: \n");
scanf("%d", &n); for
(i=1; i<=n; i++) { sum
= sum + (i*(i+1)); }
printf("Sum=%d", sum); return
0; } |
B.
Write a C program to continuously take a number as input and announce whether
the number is odd or even. Hint: use do-while loop.
|
#include <stdio.h> int main() { int i, choose
=1; do }
printf("Enter a number : \n");
scanf("%d", &i); if (i%2==0)
printf(“%d is Even\n",i); else
printf(“%d is odd\n”,i);
printf("Enter 1 to continue. \n Enter any other number to exit.”);
scanf(“%d”, &choose); } While(choose==1); Printf(“ You have selected to Exit from the
loop”); return
0; } |
C.
Write a C program to display the following pattern.
1
11
111
1111
11111
|
#include<stdio.h> int a for (a=1; a<=1; a++) {
printf(“1\n”); } for (a=1;
a<=2; a++) {
printf(“1\n”); } for (a=1;
a<=3; a++) {
printf(“1\n”); } for (a=1;
a<=4; a++) {
printf(“1\n”); } for (a=1;
a<=5; a++) {
printf(“1\n”); } return 0; }
|
D.
Write a C program to display the following pattern.
5
5 4
5 4 3
5 4 3 2
5 4 3 2 1
|
#include<stdio.h> int a for (a=5; a>4; a - -) {
printf(“%d\n”, a); } for (a=5; a>3; a - -) {
printf(“%d\n”, a); } for (a=5; a>2; a - -) {
printf(“%d\n”, a); } for (a=5; a>1; a - -) {
printf(“%d\n”, a); } for (a=5; a>0; a - -) {
printf(“%d\n”, a); } |
E.
Write a C program to display the following pattern
5 4 3 2 1
5 4 3 2
5 4 3
5 4
5
|
#include<stdio.h> int a for (a=5; a>0; a - -) {
printf(“%d\n”, a); } for (a=5; a>1; a - -) {
printf(“%d\n”, a); } for (a=5; a>0; a - -) {
printf(“%d\n”, a); } for (a=5; a>2; a - -) {
printf(“%d\n”, a); } for (a=5; a>3; a - -) {
printf(“%d\n”, a); } for (a=5; a>4; a - -) {
printf(“%d\n”, a); } return 0; } |
ADDITIONAL QUESTIONS:
1.
What is an infinite loop?
Infinite loop is the loop which
never ends.
2.
Name different types of loops.
Different types of loops are:
i) for loop
ii) while loop
iii) do-while loop
3.
What is the different between while loop and do-while loop?
The different between while loop
and do-while loop is that-
While
loop: in this loop statement(s) will execute repeatedly as long as the
condition is true. The statement can be simple or compound. Whereas,
Do-while
loop: In this loop the statement(s) will execute at least one time even
if the condition is true. The statement can be either simple or compound.
4.
What happens to a while loop when the condition is evaluate as false?
As the condition evaluate to false
in while loop, the control comes outside of the loop and execute any below
statements.
5. How
can we make our loop dynamic where the loop will run the number of times the
user wants?
We can use a variable to make our
loop dynamic where the loop will run the number of time the user wants.
6.
Name the loop that can be used to execute a group of statements as long as the
user wants?
Do-while loop
7. Why
do we use semicolon in an expression?
We used semicolon (;) in an
expression to terminate the statements.
8.
Which expression is executed before entering the for loop?
The initialization expression is
executed before entering the for loop.
9. Can
we use more than one statement in an expression of for loop?
Yes, we use more than one
statement in an expression of for loop.
10.
How can we check the divisibility of a number in programing?
We can check the divisibility of a
number in programing using modulus (%) operation and double equal operation
(==).
11.
What is the use of break statements?
Break statement is used to come
out of loop before its specific time.
12.
Write a C program to check whether a number is prime or not.
|
#include<stdio.h> int main() { int no, I,
flag=0; printf(“Enter a number:\n”); scanf(“%d”, &n); for(i=2;i<=no/2;i++) { if
(no%2==0) { flag =1; break; } } if (flag ==0 && no !=1)
printf(“%d is a prime number”, no); else printf(“%d is not a prime number”,no); return 0: ) |
13.
Write a C program to display the capital letters of English alphabet using
loop.
|
#include<stdio.h> int main() { int i; for(i=0; i<26; i++) { Printf(“%c”, i+65); } Return 0; } |
14.
Write a C program to display the even numbers form 1 to 100.
|
#include<stdio.h> int main() { int i; for(i=1; i<=100; i++) { if
(i%2==0) { Printf(“%d”,i); } } Return 0; } |
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