# 08.Control Structures. Loops and Iterations

• .
• How to find factors of a number.
#include<stdio.h>

int main(){

int num, i;

printf("Enter the number to find its factors\n");
scanf("%d", &num);

for(i = 1; i < num; ++i){

if(num % i == 0)
printf("%d, ",i);

}
printf("%d", num);
printf("\n");
}

Take base and power from user and calculate the power of that number.
#include<stdio.h>
#include<math.h>

int main(){

int base,power;
int res;
printf("Enter the base\n");
scanf("%d", & base);
printf("Enter the power\n");
scanf("%d", & power);

res = pow(base,power);

printf("%d^%d = %d\n", base,power,res);

}

Find reverse of a number
#include<stdio.h>

int main(){

long long num;
int temp;
int sum = 0;
printf("Enter the number to reverse it\n");
scanf("%lld", &num);

while(num > 0){

temp = num % 10;
sum = (sum * 10) + temp;
num = num / 10;

}
printf("%d\n", sum);
return 0;
}

• Calculate Armstrong number.

#include<stdio.h>
#include<math.h>
int main(){

int num,arm,tnum,i,temp,p,temp1;
int sCube = 0;

printf("Insert the number\n");
scanf("%d", &num);

printf("Insert the power\n");
scanf("%d", &p);
temp1 = num;
while(num > 0){

temp = num % 10;
sCube = sCube + pow(temp,p);
num = num / 10;
}

if(sCube == temp1){

printf("This is Armstrong number\n");
}
else {

printf("This is not arm strong number\n");
}
}
Find Fibonacci number.
#include<stdio.h>

int main(){

int n,i;
int n1 = 0;
int n2 = 1;
int nt;
int fib = 0;
printf("Enter the number to get Fibonacci numbers\n");
scanf("%d", &n);
printf("The Fibonacci number of %d are:\n", n);
for(i = 0; i <= n; ++i){

printf("%d\n",n1);
nt = n1 + n2;
n1 = n2;
n2 = nt;

}
return 0;
}

Right side triangle.

#include<stdio.h>

int main(){

int i, nrows,rows,col;

printf("Enter the number of rows\n");
scanf("%d", &nrows);

for(i = 1; i <= (nrows); ++i){

for(rows = (nrows-i); rows >= 0 ;--rows){
printf(" ");

}
for(col = 1; col < i+1; ++col){

printf("*");
}
printf("\n");

}
}

• Count the number in digit.
#include<stdio.h>

int main(){

long long n;
int i, lastD;
int count = 1;
printf("Enter the digit to find the count\n");
scanf("%lld", &n);

while(n > 10){
n = n / 10;
count++;

}
printf("The total number in digits is: %d\n", count);
return 0;
}

Calculate HCF (HIghest common factor)
#include<stdio.h>
int main(){

int hcf,n1,n2,temp;
int count = 0;
printf("Enter first number\n");
scanf("%d",&n1);

printf("Enter second number\n");
scanf("%d",&n2);
temp = n1>n2?n1:n2;
for(hcf = temp; hcf >= 1; --hcf ){

if(n1 % hcf == 0 && n2 % hcf == 0)

break;
}
printf("%d\n", hcf);
}
Calculate LCM (LEAST COMMON MULTIPLE)
#include<stdio.h>

int main(){

int n1,n2,lcm;
int count = 0;

printf("Enter the first number\n");
scanf("%d", &n1);

printf("Enter the second number\n");
scanf("%d", &n2);

for(lcm = 1; lcm <= (n1 * n2); ++lcm){

if(lcm % n1 == 0 && lcm % n2 ==0){

count++;
if(count == 1){
printf("%d\n", lcm);

}
}
}
}

• Check if the given number is prime or not.
#include<stdio.h>

int main(){

int num,i;
int count = 0;

printf("Enter the number to check prime or not\n");
scanf("%d", &num);

for(i = 1; i <= num; ++i){
if(num % i == 0){
count++;
}
}
if(count == 2){
printf("Prime number\n");
}
else{
printf("Not  a prime number\n");
}
}

Side ways triangle.
#include<stdio.h>

int main(){

int nrows,rows,col,i;

printf("Enter the number of rows\n");
scanf("%d", &nrows);

for(i = 1; i <= (nrows/2); ++i){

for(rows = 1; rows <= i;++rows){
printf("*");
}
for(col = (i+1); col <= nrows; ++col){
printf(" ");
}
printf("\n");
}
for(i = ((nrows/2) +1); i >= 1; --i){
for(rows = i; rows >= 1;--rows){
printf("*");

}

printf("\n");
}
}

Display A-Z.
#include<stdio.h>

int main(){
int i;
for(i = 65; i <90; ++i){

printf("%c : ", i);
}

printf("%c\n", i);

return 0;
}

• Print all the number in digits.
#include<stdio.h>

int main(){

long long num;
int temp;
printf("Enter the number to find the digits\n");
scanf("%lldd", &num);
while(num > 0){

temp = num % 10;
num = num / 10;
printf("%d\n",temp);

}
}

Sum all the number present in the array.
#include<stdio.h>
#define SIZE 4
int main(){
int arr[SIZE], n , i, sum;
printf("Enter the values in array\n");
for(i = 0; i < SIZE; ++i){
scanf("%d", &arr[i]);
}
for(i = 0;i < SIZE;++i){
sum = sum + arr[i];
}
printf("The sum of the array is : %d\n",sum );
return 0;
}
Find out factorial of a number.
#include<stdio.h>

int main(){

int n,i;
int fact = 1;
printf("Enter the number to find the factorial\n");
scanf("%d", &n);
for(i = 1; i <=n; ++i){

fact = fact * i;
}
printf("The factorial of %d is %d\n", n,fact);

return 0;
}

• Check weather the number is palindrome or not.
#include<stdio.h>

int main(){

long long num;
int temp;
int rev = 0;
printf("Enter the number to check weather it is palindrome or not\n");
scanf("%lld", &num);

while(num > 0){

temp = num % 10;
rev = (rev *10) + temp;
num = num / 10;

}
printf("%d\n", rev);
if(num == rev){
printf("The number is palindrome\n");
}
else{
printf("The number is not palindrome\n");
}
}

Pyramid triangle.
#include<stdio.h>

int main(){

int nrows,spaces,star,i;

printf("Enter the number of rows\n");
scanf("%d", &nrows);

for(i = 1; i <= nrows; ++i){

for(spaces = (nrows-i); spaces >=0; --spaces){

printf(" ");

}
for(star = 1;star <=(2 * i)-1; ++star){

printf("*");
}
for(spaces = (nrows-1); spaces >=0; --spaces){

printf(" ");
}

printf("\n");
}
}

Write a programme to find table of a number.
#include<stdio.h>
int main(){

int n,i;
int table;
int temp = 1;

printf("Enter the base of the table\n");
scanf("%d", &table);

printf("Enter the multiple of table\n");
scanf("%d", &n);
for(i = 1; i <= n; ++i){
temp = table * i;
printf("%d x %d = %d\n", table,i,temp);
}
return 0;
}

• Write a programme to find prime number in a range.
#include<stdio.h>
int main(){

int num1,num2,i,j;

printf("Enter intervals\n");
scanf("%d", &num1);

printf("-\n");
scanf("%d", &num2);

for(i = (num1+1); i <= (num2-1); ++i){

for(j = 2; j < i; ++j){

if(i % j == 0){

break;
}
}

if(i == j)
printf("%d\n", i);

}
}

• #include<stdio.h>
int main()
{
int i,n,sum;
sum=0;
/*sum of natural no.*/
printf("Enter the no\n");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum=sum+i;
}
printf("%s:sum of %d natural no is :%d",__func__,n,sum);
return 0;

}

//factorial of a no:

#include<stdio.h>
#include<math.h>
int main()
{
float i;
//factorial of a no
printf("Enter the no\n ");
scanf("%f",&i);
printf("%s:factorial of %f,%d",__func__,floor(i)),i;
return 0;
}
• #include<stdio.h>
int main()
{
int  n,i,terms;
/*multiplication table*/
printf("%s:Enter the value of no and how many terms",__func__);
scanf("%d%d",&n,&terms);
for(i=1;i<=terms;i++)
{
printf("%d*%d=%d\n",n,i,n*i);
}
return 0;
}

#include<stdio.h>
int main()
{
int  n,i,terms,sum,f1,f2;
/*fibonacci sequence*/
f1=0;f2=1;
sum=f1+f2;
printf("%s:Enter the value of no terms",__func__);
scanf("%d",&terms);
printf("%s:\n%d\t\n%d\t\n",__func__,f1,f2);
for(i=1;i<terms-1;i++)
{
sum=sum+f1;

printf("%d\t\n",sum);
f1=f2;
f2=sum;
}
return 0;
}

#include<stdio.h>
int main()
{
/*gcd of a no*/
int gcd,n1,n2,i;
printf("Enter the two n1 and n2");
scanf("%d%d",&n1,&n2);
for(i=1;i<=n1&&i<=n2;i++)
{
if(n1%i==0&&n2%i==0)
gcd=i;
printf("GCD=%d",gcd);
return 0;}

#include<stdio.h>
int main()
{
char i;
/*Display Characters*/

for(i='A';i<='Z';i++)
{
printf("%c ",i);
}
return 0;
}
#include<stdio.h>
int main()
{
int  n,flag;
/*No of digits in integer*/
printf("%s:Enter the value of no ",__func__);
scanf("%d",&n);
while(n%10!=0)
{
flag++;
n=n/10;
}
printf("%d\n",flag);

return 0;

}

• //rev of a no:
#include<stdio.h>
int main()
{
int n,rev,r;
rev=0;
printf("Enter a no.\n");
scanf("%d",&n);
while(n%10!=0)
{
r=n%10;
rev=rev*10+r;
n=n/10;
}
printf("The reversed no is:%d\n",rev);
return 0;
}
Power of no:
#include<stdio.h>
int main()
{
int n,p,i,j,pro;
pro=1;
printf("Enter a no. and power\n");
scanf("%d%d",&n,&p);
for(i=p;i>0;i--)
{
pro=pro*n;
}
printf("%d",pro);
return 0;
}
Pyramid(height defined  )
#include<stdio.h>
int main()
{
int r,c,n,sp;
printf("Enter the no of rows\n ");
scanf("%d",&n);
//n :gives no of rows
//r :tells on which row we r present
//c :denotes coloumn
//sp denotes space
for(r=1;r<=2*n-1;r++)
{
for(sp=1;sp<=2*n-r;sp++)
{
printf("   ");
}
for(c=1;c<=2*r-1;c++)
{
printf(" * ");
}
printf("\n");
}
return 0;
}

• //factors of a no
int i,n;
printf("Enter the no ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
if(n%i==0)
printf("%d ",i);
}

return 0;
}

#include<stdio.h>
#include<math.h>
int main()
{
/*armstrong*/
long int i,n,sum,temp,temp1;
double r,flag;
long int  i1,i2;
printf("Enter the value of interval i1 i2\n");
scanf("%ld%ld",&i1,&i2);
for(i=i1;i<=i2;i++)
{n=i;
sum=0;
flag=0;
temp=n;
temp1=n;
while(temp!=0)
{
flag++;
temp=temp/10;
}
while(temp1!=0)
{
r=temp1%10;
sum=sum+pow(r,flag);
temp1=temp1/10;
}
if(sum==n)
printf("%ld ",n);
}
return 0;
}
//palindrome
#include<stdio.h>
int main()
{
/*palindrome*/
int r;
long int n,temp,rev;
rev=0;
printf("Enter a no.\n");
scanf("%ld",&n);
temp=n;
while(temp!=0)
{
r=temp%10;
rev=rev*10+r;
temp=temp/10;
}

if(n==rev)
{
printf("Entered  no is palindrome");
}
else
printf("Entered  no is not  palindrome");
return 0;
}
#include<stdio.h>
int main()
{
/*prime no*/
int n,i,j,flag,i1,i2;
printf("Enter the value of interval i1 i2\n");
scanf("%d%d",&i1,&i2);
for(i=i1;i<=i2;i++)
{flag=0;
n=i;
for (j=1;j<=n;j++)
{
if(n%j==0)
flag ++;
}
if(flag==2)
{
printf("%d ",n);
}
}
return 0;
}

• //20.loop
Pattern.Q 20
#include<stdio.h>
int main()
{
int r,c,n,temp;
printf("Enter the no of rows\n ");
scanf("%d",&n);
temp=n;
for(r=1;r<=2*n-1;r++)
{
printf("%d",r);
if(r<=n)
{
for(c=1;c<=r;c++)
{
printf("* ");
}
printf("\n");
}
else
for(c=1;c<temp;c++)
{
printf("* ");
}
temp--;
printf("\n");
}

}
return 0;
}

pattern  Q.21.
#include<stdio.h>
int main()
{
int r,c,n,temp;
printf("Enter the no of rows\n ");
scanf("%d",&n);
temp=n;
for(r=1;r<=n;r++)
{
for(c=1;c<=2*temp-1;c++)
{
printf(" ");
}
temp--;
for(c=1;c<=(2*r-1);c++)
{
printf("*");
}
printf("\n");
}

return 0;
}

• #include<stdio.h>
int main()
{
int n1,n2,i,gcd,lcm;
printf("Enter the n1 and n2 ");
scanf("%d%d",&n1,&n2);
for(i=1;i<=n1&&i<=n2;i++)
{
if(n1%i==0 && n2%i==0)
gcd=i;
}
lcm=(n1*n2)/gcd;
printf("lcm of %d and %d is:%d",n1,n2,gcd);
return 0;
}

//histogram
#include<stdio.h>
#include<ctype.h>
int main()
{
//histogram
int i,j;
char x,f;
for(i=0;i<=255;i++)
{x=i;
printf("%c: %d",x,x);
f=i;
if(isalnum(i)||ispunct(i))
{
for(j=1;j<=f;j++)
{
printf("*");
}
}
printf("\n");
}

return 0;

}