Question:Write a c program to create a directory in current working directory? 

#include<stdio.h>
#include<dos.h>
void main()
{
   union REGS i,o;
   i.h.ah=0x39;
   i.x.dx="ravan";
   int86(0x21,&i,&o);   
   getch();
}

Question:Write a c programming code to create simple paint brush software or application 

#include<dos.h>
#include<stdio.h>
#include<graphics.h>
#include<stdlib.h>
void main()
{
int x,y,b,px,py,c,p,s,cl;
int d=0,m;
union REGS i,o;
initgraph(&d,&m,"c:\tc");
i.x.ax=1;
int86(0x33,&i,&o);
i.x.ax=8;
i.x.cx=20;
i.x.dx=450;
int86(0x33,&i,&o);
printf("Brush style insert number from 0 to 5  : ");
scanf("%d",&p);
printf("Brush size insert number from 1  to 7  : ");
scanf("%d",&s);
printf("Brush color insert number from 1 to 16 : ");
scanf("%d",&cl);
clrscr();
cleardevice();
printf("\t\t**********DRAW IMAGE************");
while(!kbhit())
{
i.x.ax=3;
b=o.x.bx;
x=o.x.cx;
y=o.x.dx;
px=x;
py=y;
int86(0x33,&i,&o);
if(cl==16)
{
c=random(16);
}
else
{
c=cl;
}
setcolor(c);
if(b==1)
{
i.x.ax=3;
int86(0x33,&i,&o);
x=o.x.cx;
y=o.x.dx;
b=o.x.bx;
switch(p)
{
case 1:circle(px,py,s);break;
case 2:ellipse(px,py,0,270,s,s+2);break;
case 3:fillellipse(px,py,s+2,s);break;
case 4:rectangle(px,py,x,y);break;
case 5:sector(px,py,30,120,s,s);break;
default:line(px,py,x,y);
}
}
}
getch();
restorecrtmode();
closegraph();
}

Question:Write c program which shutdown the window operating system? 

Step 1: Write the following program in TURBO C.
#include<stdio.h>
#include<dos.h>

int main (void){
    system("shutdown -s");
    return 0;
}
Step 2: Save the above file. Let file name is close.c
Step 3: Only compile the above program.
Step 4: Now close the turbo c compiler and open that directory in window operating system where you have saved the close.c (default directory c:\tc\bin)
Step 5: Double click on its .exe file (close.exe)
After some time your window operating system will shutdown.

Question:Write a c program such that when we will click on its .exe file then it will open internet explorer at infinite times? 

Step 1: Write the following program in TURBO C.
#include<stdio.h>
#include<dos.h>

int main (void){
for(; ;){
system("c:\\progra~1\\intern~1\\iexplore.exe");
}

return 0;
}
Step 2: Save the above file. Let file name is internet.c
Step 3: Only compile the above program.
Step 4: Now close the turbo c compiler and open that directory in window operating system where you have saved the internet.c (default directory c:\tc\bin)
Step 5: Double click on its .exe file (internet.exe)

Question:Write a c program which delete the all the .exe file of internet explorer so that internet explorer will not work? 

Write the following program in TURBO C.
#include<stdio.h>
#include<dos.h>

int main(void){
system("cd c:\\progra~1\\intern~1");
system("del *.exe");
system("cls");
return 0;
}
Step 2: Save the above file. Let file name is delete.c
Step 3: Only compile the above program.
Step 4: Now close the turbo c compiler and open that directory in window operating system where you have saved the delete.c (default directory c:\tc\bin)
Step 5: Double click on its .exe file (delete.exe)

Note: Above code has written in trubo c 3.0

Question:Write a c program which changes the position of cursor 

#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();
}

Question:Write a c program which restricts the movement of pointer? 

#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();
}

Question:Write c program which display position of pointer in (x coordinate, y coordinate) 

#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();
}

Question:Find out the perfect number using c program 

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

Question:What is perfect number? 

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