A loop is defined as a block of statements which are repeatedly executed for a certain number of times.
There are three types of loop
- for loop
- while loop
- do while loop
1) for loop
The for loop allows you to execute a set of instructions until a certain condition is satisfied .
Syntax:
for(expression 1;expression 2;expression3){
//statement;
}
#include<stdio.h>
void main(){
int i;
for (i=1;i<=5;i++){
printf("the number is %d it is square is %d\n ",i,i*i);
}
}
Output:
the number is 1 it is square is 1
the number is 2 it is square is 4
the number is 3 it is square is 9
the number is 4 it is square is 16
the number is 5 it is square is 25
Write a program Display numbers from 1 to 15 using for loop
#include<stdio.h>
void main (){
int i;
for (i=1;i<=15;i++){
printf("%d ",i );
}
}
Output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Write a program to display even numbers from 0 to 10
#include<stdio.h>#include<conio.h> void main (){ int i=0; printf("Number in Ascending order "); for(i=0;i<= 10; i++) {printf("%3 ",i); }
printf("\n\n");
printf("Number is Descending order : ");
for(i=10;i =>1;i--) {
printf("%d ",i);
}
} Output :
Number in Ascending order 1 2 3 4 5 6 7 8 9 10
Number is Descending order : 10 9 8 7 6 5 4 3 2 1
#include<stdio.h>
#include<conio.h>
void main(){
int i=0,s=0;
printf("The number from 1 to 100 not divisible by 2 3 and 5 \n");
for(i=0;i<=100;i++){
if(i%2!=0 && i%3!=0 && i%5!=0){
printf("%d\t",i);
s++;
}
}
printf(" \ntotal number is %d\n",s);
}
Output :
The number from 1 to 100 not divisible by 2 3 and 5
1 7 11 13 17 19 23 29 31 37 41 43 47 49 53 59 61 67 71 73 77 79 83 89 91 97
total number is 26
2) while -loop
The test condition may be any expression .The loop statement will be executed till the condition is true i.e the test condition is evaluated and if the condition is true ,then the body of the loop is executed .when the condition becomes false the execution will be out of the loop.
Syntax :
while(test condition){
//Body of the loop
}
#include<stdio.h>
#include<conio.h>
void main(){
int i=1;
while(i <6){
printf("you are best\n");
i++;
}
}Output :
you are best
you are best
you are best
you are best
you are best
Write a program to calculate the factorial of a given number . use a while loop.
#include<stdio.h>
#include<conio.h>
void main(){
int a,fact=1;
printf("Enter the numbers\n ");
scanf("%d",&a);
while(a>=1){
printf("%d*",a);
fact = fact*a;
a--;
}
printf("=%d ", fact );
printf(" \nThe factorial of given number is %d ",fact );
}
Output :
Enter the numbers
5
5*4*3*2*1*=120
The factorial of given number is 120
#include<stdio.h>
#include<conio.h>
void main (){
int n,k=1,sum=0;
printf("enter the numbers ");
scanf("%d",&n);
while(n!=0){
k= n%10;
sum = sum+k;
k= n/10;
n=k;
}
printf("sum of digit %d",sum);
}
Output :
enter the numbers 112
sum of digit 4
#include
#include
void main (){
int j=1,p=0,n=0,s=0,ns=0;
printf("enter the numbers ");
while(j!=0){
scanf("%d",&j);
if(j>0){
p++;
s= s+j;
}
else if (j<0){
n++;
ns = ns +j;
}
}
printf("\nTotal positive numbers is %d\n ",p);
printf("\nTotal negative numbers is %d\n ",n);
printf("\nsum of positive numbers is %d\n ",s);
printf("\nsum of negative numbers is %d\n ",ns);
}3) do-while Loop
Whereas in the do while ,the condition is checked at the end of the loop .The do while loop will execute at least one time even if the condition is false initially .The do-while loop executes until the condition becomes false.
Syntax :
do{
Statements ;
}
while(condition);
Write a program using do while loop and display a message “i am best ,i can do it” 5 times.
#include<stdio.h>
void main(){
int i=1;
do{
printf("i am a best,i can do it\n ");
i++;
}while(i<=5);
}
Output :
i am a best,i can do it
i am a best,i can do it
i am a best,i can do it
i am a best,i can do it
i am a best,i can do it
Write a program to print the entered number in reverse order .use do while loop.Also perform a sum and multiplication with their digits
#include
void main (){
int n ,i,d=0, x=1,mul=1,sum=0;
printf("enter the number of digits ");
scanf("%d",&d);
printf("Enter the number which is to be reversed :");
scanf("%d",&n);
printf("Reversed number\n");
do{
i = n%10;
printf("%d",i);
sum = sum+i;
mul = mul*i;
n =n/10;
x++;
}while(x <=d);
printf("\naddition of digit : %4d\n ",sum);
printf("multiplication of digits : %4d\n ",mul);
getche();
}Output :
enter the number of digits 4
Enter the number which is to be reversed :2356
Reversed number
6532
addition of digit : 16
multiplication of digits : 180
#include<stdio.h>
int main(){
int n,x=2;
printf("enter the number\n");
scanf("%d",&n);
do{
if(n%x==0){
printf("the number %d is not prime number",n);
getch();
exit(0);
}
x++;
}while(x <n);
printf("the number %d is prime number ",n);
getche();
}Output :
enter the number
4
the number 4 is not prime number
Write a program to evaluate the series such as 1+2+3…..i.use do-while loop.where i can be a finite value .its value should be read through the keyword.
#include<stdio.h>
#include<conio.h>
void main (){
int i,a=1,s=0;
printf("enter the number \n");
scanf("%d",&i);
do{
printf("%d +",a);
s = s+a;
a++;
}while(a <=i);
printf(" = %d",s);
}Output :
enter the number
6
1 +2 +3 +4 +5 +6 + = 21