//11) Write a C program that prompts the user to choose an operation to do on 2 input integers. The
//operations are addition, subtraction, multiplication, and division. Note: the program should not
//allow the division by zero.
#include<stdio.h>
int main()
{
int x,y,op;
printf("enter integer number of x:");
scanf("%d",&x);
printf("enter integer number of y:");
scanf("%d",&y);
printf("choose an operation:\n1 to addition\n2 to subtraction\n3 to multiplication\n4 to division\n");
scanf("%d",&op);
switch(op)
{
case 1:
printf("addition is %d",x+y);
break;
case 2:
printf("subtraction is %d",x-y);
break;
case 3:
printf(" multiplication is %d",x*y);
break;
case 4:
if(y==0)
printf("the program not allow the division by zero");
else
printf(" division is %d",x/y);
break;
default:
printf("choose from 1 to 4");
}
}
//---------------------------------------------------------------------------------------------------
//12) Write a C program that will print the following pattern:
#include<stdio.h>
int main()
{
int rows,i,k;
scanf("%d",&rows);
for(i=rows ; i>=1 ;i--)
{
for(k=i;k>=1;k--)
{
printf("*");
}
printf("\n");
}
}
//---------------------------------------------------------------------------------------------------
//13) Write a C program that will print the following pattern:
//#include<stdio.h>
int main()
{
int rows,i,l,s;
printf("enter number of rows:");
scanf("%d",&rows);
s=rows*2;
for(i=1 ; i<=s ;i++)
{
for(l=1; l<=i ;l++)
{
printf("*");
}
printf("\n");
i++;
}
int k,m;
for(k=s;k>=1;k--)
{
for(m=k-1;m>=1;m--)
{
printf("*");
}
printf("\n");
k--;
}
}
//---------------------------------------------------------------------------------------------------
//14) Write a C program that finds the sum of the first n natural numbers
#include<stdio.h>
int main()
{
int n,i,sum=0;
printf("enter value of n:");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
sum+=i;
}
printf("sum is %d",sum);
}
//---------------------------------------------------------------------------------------------------
//15) Write a C code that finds the sum of the digits of a number.
#include<stdio.h>
int main()
{
int n,z,sum=0;
printf("enter number of n:");
scanf("%d",&n);
while(n!=0)
{
z=n%10;
sum+=z;
n/=10;
}
printf("the sum of the digits of a number = %d",sum);
}