Code:
#include<stdio.h>
#include<conio.h>

char *str,select;

main()
{
int item;
      do
      {
clrscr();
printf("1. FACTORIAL\n");
printf("2. FIBONACCI\n");
printf("3. EUCLID\n");
printf("4. EXIT\n");
printf("SELECT AN OPTION:\n");
scanf("&#37;d",&item);
if (item==1)
{
clrscr();
{
long a,b,c;
gotoxy(1,1);
printf("RECURSIVE\n");
printf("Enter a Number: ");
scanf("%li",&a);
c=1;
b=1;
do
{
printf("%li = %li*%li=%li\n",b,b,c,b*c);
c*=b;
b++;
}while(b<=a);
printf("FACTORIAL IS %li",c);
}
getch();
}

else if (item==2)
{	
clrscr();
{
int f,a,b,c,ctr;
gotoxy(1,1);
printf("ITERATION\n");
printf("ENTER A NUMBER: ");
scanf("%d",&c);
f=1;
a=1;
if(c<1)
printf("TRY AGAIN");
else
printf("0\t");
for(ctr=1;ctr<=c;ctr++)
{
printf("%d\t",f);
if(ctr>1)
{
b=f+a;
a=f;
f=b;
}
}
getch();
}
}

else if (item==3)

clrscr();
{
long a,b,q,r;
gotoxy(1,1);
do
{
printf("ENTER IST  NUMBER :");
scanf("%li",&a);
printf("ENTER 2ND NUMBER :");
scanf("li",&b);
}
while(b>a);
do
{
q=a/b;
r=a%b;
printf("%li=%li(%li)+li \n",a,b,q,r);
a=b;
b=r;
}
while(r>0);
printf("GCD is %li",a);
getch();
}}

else if (item==4)
{
break;
}
else
{
printf("Invalid Input! Press Any Key to Continue...");
getch();
}
}while(item!="2");
getch();
}