Difference between Recursion and Iteration
Last Updated :
28 May, 2025
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A program is called recursive when an entity calls itself. A program is called iterative when there is a loop (or repetition).
Example: Program to find the factorial of a number
// C++ program to find factorial of given number
#include<bits/stdc++.h>
using namespace std;
// ----- Recursion -----
// method to find factorial of given number
int factorialUsingRecursion(int n)
{
if (n == 0)
return 1;
// recursion call
return n * factorialUsingRecursion(n - 1);
}
// ----- Iteration -----
// Method to find the factorial of a given number
int factorialUsingIteration(int n)
{
int res = 1, i;
// using iteration
for (i = 2; i <= n; i++)
res *= i;
return res;
}
// Driver method
int main()
{
int num = 5;
cout << "Factorial of " << num <<
" using Recursion is: " <<
factorialUsingRecursion(5) << endl;
cout << "Factorial of " << num <<
" using Iteration is: " <<
factorialUsingIteration(5);
return 0;
}
// This code is contributed by mits
// C program to find factorial of given number
#include <stdio.h>
// ----- Recursion -----
// method to find factorial of given number
int factorialUsingRecursion(int n)
{
if (n == 0)
return 1;
// recursion call
return n * factorialUsingRecursion(n - 1);
}
// ----- Iteration -----
// Method to find the factorial of a given number
int factorialUsingIteration(int n)
{
int res = 1, i;
// using iteration
for (i = 2; i <= n; i++)
res *= i;
return res;
}
// Driver method
int main()
{
int num = 5;
printf("Factorial of %d using Recursion is: %d\n", num,
factorialUsingRecursion(5));
printf("Factorial of %d using Iteration is: %d", num,
factorialUsingIteration(5));
return 0;
}
// This code is contributed by mits
// Java program to find factorial of given number
class GFG {
// ----- Recursion -----
// method to find factorial of given number
static int factorialUsingRecursion(int n)
{
if (n == 0)
return 1;
// recursion call
return n * factorialUsingRecursion(n - 1);
}
// ----- Iteration -----
// Method to find the factorial of a given number
static int factorialUsingIteration(int n)
{
int res = 1, i;
// using iteration
for (i = 2; i <= n; i++)
res *= i;
return res;
}
// Driver method
public static void main(String[] args)
{
int num = 5;
System.out.println("Factorial of " + num
+ " using Recursion is: "
+ factorialUsingRecursion(5));
System.out.println("Factorial of " + num
+ " using Iteration is: "
+ factorialUsingIteration(5));
}
}
# Python3 program to find factorial of given number
# ----- Recursion -----
# method to find factorial of given number
def factorialUsingRecursion(n):
if (n == 0):
return 1;
# recursion call
return n * factorialUsingRecursion(n - 1);
# ----- Iteration -----
# Method to find the factorial of a given number
def factorialUsingIteration(n):
res = 1;
# using iteration
for i in range(2, n + 1):
res *= i;
return res;
# Driver method
num = 5;
print("Factorial of",num,"using Recursion is:",
factorialUsingRecursion(5));
print("Factorial of",num,"using Iteration is:",
factorialUsingIteration(5));
# This code is contributed by mits
// C# program to find factorial of
// given number
using System;
class GFG
{
// ----- Recursion -----
// method to find factorial of
// given number
static int factorialUsingRecursion(int n)
{
if (n == 0)
return 1;
// recursion call
return n * factorialUsingRecursion(n - 1);
}
// ----- Iteration -----
// Method to find the factorial of
// a given number
static int factorialUsingIteration(int n)
{
int res = 1, i;
// using iteration
for (i = 2; i <= n; i++)
res *= i;
return res;
}
// Driver Code
public static void Main(String[] args)
{
int num = 5;
Console.WriteLine("Factorial of " + num +
" using Recursion is: " +
factorialUsingRecursion(5));
Console.WriteLine("Factorial of " + num +
" using Iteration is: " +
factorialUsingIteration(5));
}
}
// This code has been contributed by Rajput-Ji
<script>
// JavaScript program to find factorial of given number
// ----- Recursion -----
// method to find factorial of given number
function factorialUsingRecursion(n)
{
if (n == 0)
return 1;
// recursion call
return n * factorialUsingRecursion(n - 1);
}
// ----- Iteration -----
// Method to find the factorial of a given number
function factorialUsingIteration(n)
{
var res = 1, i;
// using iteration
for (i = 2; i <= n; i++)
res *= i;
return res;
}
// Driver method
var num = 5;
document.write("Factorial of " + num
+ " using Recursion is: "
+ factorialUsingRecursion(5)+"<br>");
document.write("Factorial of " + num
+ " using Iteration is: "
+ factorialUsingIteration(5));
// This code is contributed by shivanisinghss2110
</script>
<?php
// PHP program to find factorial of given number
// ----- Recursion -----
// method to find factorial of given number
function factorialUsingRecursion($n)
{
if ($n == 0)
return 1;
// recursion call
return $n * factorialUsingRecursion($n - 1);
}
// ----- Iteration -----
// Method to find the factorial of a given number
function factorialUsingIteration($n)
{
$res = 1;
// using iteration
for ($i = 2; $i <= $n; $i++)
$res *= $i;
return $res;
}
// Driver method
$num = 5;
print("Factorial of ".$num." using Recursion is: ".
factorialUsingRecursion(5)."\n");
print("Factorial of ".$num." using Iteration is: ".
factorialUsingIteration(5)."\n");
// This code is contributed by mits
?>
Output
Factorial of 5 using Recursion is: 120 Factorial of 5 using Iteration is: 120
Difference between Iteration and Recursion
The following table lists the major differences between iteration and recursion:
Property | Recursion | Iteration |
|---|---|---|
| Definition | Function calls itself. | A set of instructions repeatedly executed. |
| Application | Certain problems can be solved quite easily using recursion like Towers of Hanoi (TOH), Inorder/Preorder/Postorder Tree Traversals, DFS of Graph, etc. | In general iterative solutions are preferred over recursive solutions as there is no extra overhead required for recursion. |
| Termination | Through base case, where there will be no function call. | When the termination condition for the iterator ceases to be satisfied. |
| Usage | Used in academics to teach foundations and logic. Also works as a foundation for Dynamic Programming and Divide and Conquer algorithms. | Preferred in general. |
| Code Size | Can be smaller code size for inherently recursive problems. | Can be larger for naturally recursive problems. |
Time Complexity | In general time complexity is higher or same. The time complexity especially become higher for the problems that can be optimized using dynamic programming | Lower or same. |
| Space Complexity | In general, the auxiliary space is either higher. Can be same in same cases where we need an explicit stack to simulate recursion like tree traversals, merge sort, etc. | Generally lower |
| Overhead | Possesses overhead of repeated function calls. | No overhead as there are no function calls in iteration. |
