Recursion

C

src/c/basics/06-recursive-factorial.c

#include <stdio.h>

// long allows factorial up to 20
long factorial(int num)
{
    if (num == 1)
        return 1;
    else
        return (num * factorial(num - 1));
}

int main()
{
    int lim = 10, i;
    long fact;

    for (i = 1; i < lim; i++)
    {
        fact = factorial(i);
        printf("%d! = %ld\n", i, fact);
    }
    return 0;
}

C++

src/cpp/basics/06-recursive-fibonacci.cpp

#include <iostream>
using namespace std;

long fibonacci(int n)
{
    if (n <= 1)
        return n;
    else
        return (fibonacci(n - 1) + fibonacci(n - 2));
}

int main()
{
    int lim = 45, i;
    long fib;

    for (i = 0; i < lim; i++)
    {
        fib = fibonacci(i);
        cout << "F(" << i << ") = " << fib << endl;
    }
    
    return 0;
}

info

Recursion enables us to solve certain types of problems very elegantly, however there are certain downside to large numbers of recursive function calls; it requires large amount of stack memory, and program might crash with stack overflow.