thought for the day: to understand the concept of recursion, you must first understand what is recursion ;-)

Answer 1

It's just when a function or method calls itself.

For example: factorial function

Say you were to enter a 3 as the parameter, it would return 1 * 2 * 3. Or if you enter 1 or 0, returns 1. And if the parameter doesn't have a factorial it returns -1.

long long factorial(long long num) {
switch (num) {
case 0:
case 1:
return 1;
default:
if (num > 0)
return factorial(num - 1) * num;
return -1;
}
}

Answer 2

Some simple example of reccursive function calcutating N fibonacci's number:

int fib(int n)
{
if(n==1 || n==2) return n;
return fib(n-1)+fib(n-2)
}