Recursion

Recursion is derived from the word recur which means repetition
 There are two basic requirement for recursion:
   i) The function must call itself again and again
   ii) The function must have an exit condition.
 When to use recursion:
     Recursion can be used for any function involving loop i.e, all loops can be converted into recursion

• A recursion procedure or function is one that repeats itself through calls made on it.
• Repeat calls are terminated as soon as certain condition is satisfied.
• Every recursive function must contain a way to get out of the recursive process
• Recursive process is complex and involved
• Recursive function may be defined as a repeated iteration , which calls itself until a certain condition is met.

Eg:
      void recurse ()
       {
             recurse ();  //Function call itself
        }
        int main ()
         {
            recurse ();   // set off recursion
             return();
            }

Example of Recursion

/* Sum of N nos. through recursion */
# include <iostream.h>
int add (int x);
 main()
{
int n;
cout<<"Enter any positive no. \n";
cin>>n;
cout<<"The sum of first"<<n<<"integer="<<add(n)<<endl;
return 0;
}
int add (int n)
{
if (n==0)
return 0;
else return[n+add(n-1)]
}