# Difference Between Recursion and Iteration

Recursion and Iteration both repeatedly execute the set of instructions. Recursion occurs when a statement in a function calls itself repeatedly. The iteration occurs when a loop repeatedly executes until the controlling condition becomes false. The basic difference between recursion and iteration is that recursion is a process always applied to a function and iteration is applied to the set of instructions which we want to be executed repeatedly.

Read through this article to find out more about Recursion and Iteration and how they are different from each other.

## What is Recursion?

Recursion is defined as a process in which a function calls itself repeatedly. Recursion uses selection structure. If the recursion step does not reduce the problem in a manner that converges on some condition, called base condition, then an infinite recursion occurs. An infinite recursion can crash the system. Recursion terminates when a base case is recognized.

Because of the overhead of maintaining the stack, the recursion process is usually slower than iteration. Also, recursion uses more memory than iteration. However, it makes the code smaller, thus it is an amazing technique that makes it easier to read and write the code.

## What is Iteration?

Iteration is defined as the repetition of computational or mathematical procedure that continues until the controlling condition becomes false. It uses repetition structure. If the loop condition test never becomes false, then an infinite loop occurs with iteration. This infinite looping uses CPU cycles repeatedly. An iteration terminates when the loop condition fails. Iteration consumes less memory, but makes the code longer which is difficult to read and write.

## Difference between Recursion and Iteration

The following table highlights all the important differences between recursion and iteration −

Recursion

Iteration

Recursion uses the selection structure.

Iteration uses the repetition structure.

Infinite recursion occurs if the step in recursion doesn't reduce the problem to a smaller problem. It also becomes infinite recursion if it doesn't convert on a specific condition. This specific condition is known as the base case.

An infinite loop occurs when the condition in the loop doesn't become False ever.

The system crashes when infinite recursion is encountered.

Iteration uses the CPU cycles again and again when an infinite loop occurs.

Recursion terminates when the base case is met.

Iteration terminates when the condition in the loop fails.

Recursion is slower than iteration since it has the overhead of maintaining and updating the stack.

Iteration is quick in comparison to recursion. It doesn't utilize the stack.

Recursion uses more memory in comparison to iteration.

Iteration uses less memory in comparison to recursion.

Recursion reduces the size of the code.

Iteration increases the size of the code.

## Conclusion

Recursion uses selection structure and reduces the size of the code. Iteration, on the other hand, the iteration uses repetition structure and increases the size of the code. However, iteration uses less memory as compared to recursion.

Updated on: 13-Apr-2023

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