1. 1
1. Write a c program to swap two numbers.
void main()
{
int a,b,c;
clrscr();
printf("n Enter two no ");
scanf("%d%d",&a,&b);
printf("n Before Swaping value of a and b %d %d",a,b);
c=a;
a=b;
b=c;
printf("n After Swaping value of a and b %d %d",a,b);
getch();
}
2. Write a c program to swap two numbers without using third
variable.
#include<stdio.h>
#include<conio.h>
int main()
{
int a=5,b=10;
//process one
a=b+a;
b=a-b;
a=a-b;
printf("a= %d b= %d",a,b);
return 0;
getch();
}
3. Write a c program to swap two numbers without using third
variable.
#include<stdio.h>
#include<conio.h>
int main()
{
int a=5,b=10;
//process one
a=b+a;

2. 2
b=a-b;
a=a-b;
printf("a= %d b= %d",a,b);
return 0;
getch();
}
1. How to calculate power of a number in c
#include<stdio.h>
int main(){
int pow,num,i=1;
long int sum=1;
printf("nEnter a number: ");
scanf("%d",&num);
printf("nEnter power: ");
scanf("%d",&pow);
while(i<=pow){
sum=sum*num;
i++;
}
printf("n%d to the power %d is: %ld",num,pow,sum);
return 0;
}
2. Code for swapping in c
#include<stdio.h>
int main(){
int a,b,temp;
printf("Enter any two integers: ");
scanf("%d%d",&a,&b);
printf("Before swapping: a = %d, b=%d",a,b);
temp= a;
a=b;
b=a;
printf("nAfter swapping: a = %d, b=%d",a,b);
return 0;
}

3. 3
3. Count the number of digits in c
#include<stdio.h>
int main(){
int num,count=0;
printf("Enter a number: ");
scanf("%d",&num);
while(num){
num=num/10;
count++;
}
printf("Total digits is: %d",count);
return 0;
}
Sample output:
Enter a number: 23
Total digits is: 2
4. C code to count the total number of digit using
for loop
#include<stdio.h>
int main(){
int num,count=0;
printf("Enter a number: ");
scanf("%d",&num);
for(;num!=0;num=num/10)
count++;
printf("Total digits is: %d",count);
return 0;
}
Sample output:
Enter a number: 456
Total digits is: 3
5. Simple program of c find the largest number
#include<stdio.h>
int main(){
int n,num,i;
int big;
printf("Enter the values of n: ");
scanf("%d",&n);

4. 4
printf("Number %d",1);
scanf("%d",&big);
for(i=2;i<=n;i++){
printf("Number %d: ",i);
scanf("%d",&num);
if(big<num)
big=num;
}
printf("Largest number is: %d",big);
return 0;
}
Sample Output:
Enter the values of n:
Number 1: 12
Number 2: 32
Number 3: 35
Largest number is: 35
6. C program to calculate sum of digits
#include<stdio.h>
int main(){
int num,sum=0,r;
printf("Enter a number: ");
scanf("%d",&num);
while(num){
r=num%10;
num=num/10;
sum=sum+r;
}
printf("Sum of digits of number: %d",sum);
return 0;
}
Sample output:
Enter a number: 123
Sum of digits of number: 6

5. 5
7. Sum of digits of a number in c using for loop
#include<stdio.h>
int main(){
int num,sum=0,r;
printf("Enter a number: ");
scanf("%d",&num);
for(;num!=0;num=num/10){
r=num%10;
sum=sum+r;
}
printf("Sum of digits of number: %d",sum);
return 0;
}
8. Sum of digits in c using recursion
#include<stdio.h>
int getSum(int);
int main(){
int num,sum;
printf("Enter a number: ");
scanf("%d",&num);
sum = getSum(num);
printf("Sum of digits of number: %d",sum);
return 0;
}
int getSum(int num){
static int sum =0,r;
if(num!=0){
r=num%10;
sum=sum+r;
getSum(num/10);
}

6. 6
return sum;
}
Sample output:
Enter a number: 45
Sum of digits of number: 9
9.Write a c program to find out L.C.M. of two
numbers.
Definition of LCM (Least common multiple):
LCM of two integers is a smallest positive integer
which is multiple of both integers that it is divisible
by the both of the numbers.
For example: LCM of two integers 2 and 5 is 10 since 10
is the smallest positive numbers which is divisible by
both 2 and 5.
#include<stdio.h>
int main(){
int n1,n2,x,y;
printf("nEnter two numbers:");
scanf("%d %d",&n1,&n2);
x=n1,y=n2;
while(n1!=n2){
if(n1>n2)
n1=n1-n2;
else
n2=n2-n1;
}
printf("L.C.M=%d",x*y/n1);
return 0;
}

7. 7
10. Write a c program to find out the sum of
infinite G.P. series
Definition of geometric progression (G.P.):
A series of numbers in which ratio of any two
consecutive numbers is always a same number that is
constant. This constant is called as common ratio.
Example of G.P. series:
2 4 8 16 32 64
Here common difference is 2 since ratio any two
consecutive numbers for example 32 / 16 or 64/32 is
2.
Sum of G.P. series:Sn =a(1–rn+1
)/(1-r)
Tn term of G.P. series:Tn = arn-1
Sum of infinite G.P. series:
Sn = a/(1-r) if 1 > r
= a/(r-1) if r > 1
#include<stdio.h>
int main(){
float a,r;
float sum=0;
printf("Enter the first number of the G.P. series:
");
scanf("%f",&a);
printf("Enter the common ratio of G.P. series: ");
scanf("%f",&r);
if(1 > r)
sum = a/(1-r);
else
sum = a/(r-1);
printf("nSum of the infinite G.P. series:
%f",sum);
return 0;
}

8. 8
Sample output:
Enter the first number of the G.P. series: 1
Enter the common ratio of G.P. series: .5
Sum of the infinite G.P. series: 2.000000
Enter the first number of the G.P. series: 5
Enter the common ratio of G.P. series: 2
Sum of the infinite G.P. series: 5.000000