Iteration

What is Iteration?

Iteration in computer programming is the process of repeating a block of code (i.e., a set of instructions) in a sequence for a specified number of times, or until a certain condition is met. When a sequence of instructions is executed repeatedly, it forms a loop.

Techopedia Explains the Iteration Meaning

An image explaining the meaning of iteration

Iteration is the repetition of a process in a computer program, usually done with the help of loops. In simple terms, iteration means doing something over and over again in a program. This repetition can happen a set number of times or until a certain condition is met.

This allows programmers to automate repetitive tasks. For example, if you wanted to print “Hello” five times to the console in a program, you would use iteration to repeat the printing process five times.

Origins and History of Iteration

The word itself comes from Latin and means ‘to repeat’ or ‘to do again.’ In everyday language, it refers to doing something over and over.

One of the earliest documented instances of iterative methods in mathematics is attributed to Carl Friedrich Gauss. In a letter dated December 26, 1823, Gauss described a method that can be considered iterative.

In computing, documented history of iteration dates back to the e lectronic numerical integrator and computer (ENIAC) in the 1940s when programmers used iteration to perform complex calculations.

How Iteration Works

A flowchart showing how iteration works

Iteration works by repeating instructions a set number of times or until a condition is met and is controlled by loops.

It involves:

Initialization
Condition evaluation
Iteration
Update (increment/decrement)

This repeats until the condition is false, ending the loop.

Components of Iteration

The process of iteration typically includes the following components:

Initialization

Executed at the start of a loop, setting up initial conditions or variable values.

Condition

Evaluated at the start of each iteration to determine loop termination.

Increment/Decrement

Executed at the end of each iteration to update loop variables.

Iteration vs. Recursion Comparison Table

Iteration	Recursion
Repeat a block of code a specified number of times or until a condition is met.	Function calls itself with updated data to solve problems in smaller pieces.
Uses loops (for/while) to control repeats.	Requires a base case that determines when it should stop.
Loops are simpler to execute, making iteration faster and more memory-efficient.	Can be slower and use more memory due to the overhead of function calls.
Better for most repeated tasks that don’t have a self-similar structure.	Better for self-similar problems where you can break things down into smaller versions.
Use cases: processing collections, searching and sorting algorithms, repetitive calculations.	Use cases: binary search, graph traversal, merge sort.

Types of Iterations in Computer Programming

There are two main types of iterations:

Count-controlled loops (definite iteration)

Involves repeating a block of code when you know exactly how many times you want to repeat a task. This is achieved using ‘for’ loops, which iterate over a specified range of values.

Condition-controlled loops (indefinite iteration)

Involves repeating a block of code until a specific condition is met. This is achieved using ‘while’ loops, where the loop continues executing as long as the condition remains true.

Applications of Iteration

Example applications include the following:

Cryptography
Database operations
Game development
Image processing
Machine learning (ML)
Recursive algorithms
Repetitive calculations
Searching and Sorting
Web scraping

Iteration Example

Below is an example of an iteration programming language.

Consider a database table containing 1000 student records. Each record contains the following fields:

First name
Last name
Roll no

If one wants to copy all the student records from the database and print them, the best way to retrieve the record is to iterate or loop through each record. It can be executed using the for loop statement as shown below:

for (int i=0;i<1000;i++)

{

Print first name and last name from table

}

In the above example, ‘i’ is an iterator starting from the first student record to the last student record.

Iteration Benefits

Iteration offers several benefits in programming:

Adaptability to changing conditions
Efficiency in repetitive tasks
Flexibility to adjust for varying scenarios
Scalability to handle large datasets
Simplifies complex problem-solving
Testing and debugging incrementally

The Bottom Line

Iteration is a fundamental concept in programming, enabling the repetition of code blocks, allowing programmers to automate repetitive tasks, and creating flexible algorithms. Iteration is faster and more memory-efficient than alternatives like recursion and is useful for tasks such as calculations, searching, sorting, and processing data.