Program to find twin prime numbers.

Program to find twin prime numbers. Please comment if you need help.

#include<stdio.h>
void main( )
{
int  i,n,k,r,a[50],p;
printf("nEnter the range:  ");
scanf("%d", &r);
i=1;
p=0;
while(i<=r)
{
k=0;
n=1;
while(n<=i)
{
if( i%n==0 )
k++;
n++;
}
if(k==2)
{
a[p]=i;
p++;
}
i++;
}
for(n=0;n<p;n++)
{
if(a[n+1] - a[n]==2)
printf("\n%d and %d are twin primes", a[n], a[n+1]);
}
}

Program to swap two numbers

Program to swap two numbers with address and pointers. Again, a necessary program for all amateur CSE students.

#include<stdio.h>
void swap(int *x,int *y)
{
 int temp;
 temp=*x;
 *x=*y;
 *y=temp;
}
void main()
{
  int a,b;
  printf("Enter the number a:");
  scanf("%d",&a);
  printf("\n Enter the number b:");
  scanf("%d",&b);
  swap(&a,&b);
  printf("\n a contain %d",a);
  printf("\n b contain %d",b);
}

Program to sort numbers in ascending and descending order

Simple C program to arrange numbers in an array in ascending and descending order. If you need help, let me know.

#include<stdio.h> main() { int a[50],n,i,j,t; printf("neter the number of numbers in aray"); scanf("%d",&n); printf("enter the number"); for(i=0;i<n;i++) { scanf("%d",&a[i]); } for(i=0;i<n;i++) { for(j=0;j<(n-i)-1;j++) { if(a[j]>a[j+1]) { t=a[j]; a[j]=a[j+1]; a[j+1]=t; } } } printf("array in ascending"); for(i=0;i<n;i++) { printf("%d",a[i]); } printf("decending"); for(i=0;i<n;i++) { for(j=0;j<(n-i)-1;j++) { if(a[j]<a[j+1]) { t=a[j]; a[j]=a[j+1]; a[j+1]=t; } } } for(i=0;i<n;i++) { printf("%d",a[i]); } printf("\n"); }

Addition, multiplication and transpose of matrices

This is a program for the addition, multiplication and transpose of matrices. If you have any doubts, please let me know.

#include<stdio.h> main() { int m,n,i,j,k,p,q,r,a[25][25],b[25][25],c[25][25],ch; printf("\n Enter the rows and columns"); scanf("%d %d",&m,&n); printf("\n Enter the value of the array"); for(i=0;i<m;i++) { for(j=0;j<n;j++) scanf("%d",&a[i][j]); } printf("\n MENU \n 1)addition 2)multiplication 3)transpose \n Enter your choice"); scanf("%d",&ch); if(ch==1) { printf("\n Enter the value of the array b"); for(i=0;i<m;i++) { for(j=0;j<n;j++) { scanf("%d",&b[i][j]); c[i][j]=a[i][j]+b[i][j]; } } printf("\n the array is \n"); for(i=0;i<m;i++) { for(j=0;j<n;j++) { printf(" %d ",c[i][j]); } printf("\n"); } } if(ch==2) { printf("\n Enter the value of array b"); for(i=0;i<m;i++) { for(j=0;j<n;j++) { scanf("%d",&b[i][j]); } } for(i=0;i<m;i++) { for(j=0;j<n;j++) { c[i][j]=0; for(k=0;k<n;k++) { c[i][j]=c[i][j]+a[i][k]*b[k][i]; } } } printf("\n the new array is \n"); for(i=0;i<m;i++) { for(j=0;j<n;j++) { printf(" %d ",c[i][j]); } printf("\n"); } } if(ch==3) { for(i=0;i<m;i++) { for(j=0;j<n;j++) b[i][j]=a[j][i]; } printf("\n the new array is \n"); for(i=0;i<m;i++) { for(j=0;j<n;j++) { printf(" %d ",b[i][j]); } printf("\n"); } } }

Program to check for a leap year.

Simple C program to check whether a year is leap year or not. If you have any doubts, please let me know.

#include<stdio.h> void main() { int num; printf ("enter number"); scanf ("%d",&num); if(num%4==0&&num%100!=0)||(num%400==0) { printf ("leap year"); } else { printf ("no"); } }

Program to print out largest of 3 numbers

Program to print out the largest of 3 numbers. If you have any doubts, please let me know.


#include<stdio.h> void main() { int large,x,y,z; printf("enter the 3 numbers"); scanf("%d",&x); scanf("%d",&y); scanf("%d",&z); large=(x>y?(x>z?x:z):(y>z?y:z)); printf("%d",large); }