#include<dos.h>
#include<stdio.h>
void main()
{
union REGS i,o;
i.h.ah=2;   //positioning the cursor 
i.h.bh=0;
i.h.dh=30;   
i.h.dl=45;
int86(0x10,&i,&o);
printf("World");
getch();
}

#include <dos.h>
#include <stdio.h>
void main()
{
union REGS i,o;
//show mouse pointer
i.x.ax=1;
int86(0x33,&i,&o);
//x coordinate restriction
i.x.ax=7;
i.x.cx=20;
i.x.dx=300;
int86(0x33,&i,&o);
//y coordinate restriction
i.x.ax=8;
i.x.cx=50;
i.x.dx=250;
int86(0x33,&i,&o);
getch();
}

#include<dos.h>
#include<stdio.h>
void main()
{
union REGS i,o;
int x,y,k;
//show mouse pointer
i.x.ax=1;
int86(0x33,&i,&o);
while(!kbhit())  //its value will false when we hit key in the key board
{
i.x.ax=3;    //get mouse position
x=o.x.cx;
y=o.x.dx;
clrscr();
printf("(%d , %d)",x,y);
delay(250);
int86(0x33,&i,&o);
}
getch();
}

Code example 1:
1. C program to check perfect number
#include<stdio.h>
int main(){
  int n,i=1,sum=0;

  printf("Enter a number: ");
  scanf("%d",&n);

  while(i<n){
      if(n%i==0)
           sum=sum+i;
          i++;
  }
  if(sum==n)
      printf("%d is a perfect number",i);
  else
      printf("%d is not a perfect number",i);

  return 0;
}
Sample output:
Enter a number: 6
6 is a perfect numberCode example 2:
1. C program to find perfect numbers
2. C perfect number code
3. Perfect number program in c language
#include<stdio.h>
int main(){
  int n,i,sum;
  int min,max;

  printf("Enter the minimum range: ");
  scanf("%d",&min);

  printf("Enter the maximum range: ");
  scanf("%d",&max);

  printf("Perfect numbers in given range is: ");
  for(n=min;n<=max;n++){
    i=1;
    sum = 0;

    while(i<n){
      if(n%i==0)
           sum=sum+i;
          i++;
    }

    if(sum==n)
      printf("%d ",n);
  }

  return 0;
}
Sample output:
Enter the minimum range: 1
Enter the maximum range: 20
Perfect numbers in given range is: 6Code example 3:
3. C program to print perfect numbers from 1 to 100
#include<stdio.h>
int main(){
  int n,i,sum;
 
  printf("Perfect numbers are: ");
  for(n=1;n<=100;n++){
    i=1;
    sum = 0;

    while(i<n){
      if(n%i==0)
           sum=sum+i;
          i++;
    }

    if(sum==n)
      printf("%d ",n);
  }

  return 0;
}
Output:
Perfect numbers are: 6 28

Perfect number is a positive number which sum of all positive divisors excluding that number is equal to that number. For example 6 is perfect number since divisor of 6 are 1, 2 and 3.  Sum of its divisor is
1 + 2+ 3 =6

Note: 6 is the smallest perfect number.

Next perfect number is 28 since 1+ 2 + 4 + 7 + 14 = 28
Some more perfect numbers: 496, 8128