Source: https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-6-2-iteration

[Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [GCSE](https://senecalearning.com/en-gb/revision-notes/gcse.md) › [Coding](https://senecalearning.com/en-gb/revision-notes/gcse/coding.md) › [National Curriculum](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum.md) › Iteration

# Iteration

Coding: Introduction to Python v3, topic 1.6.2

## Iteration

Iteration allows a group of statements to be repeated multiple times. Iteration statements are often called loops.

### Indefinite iteration

![Indefinite iteration](https://image-v2.cdn.app.senecalearning.com/2018-08/74d82980-f764-423c-a8bb-3382813f616d/Indefinite%20Iteration.png)

- A block of code will repeat whilst a specified condition is true.
- For example: the while loop will continue to execute an indented code block while a certain condition is true.

### Definite iteration

![Definite iteration](https://image-v2.cdn.app.senecalearning.com/2018-08/f7192a21-19f2-464e-9abb-c6f34f11ab24/Definite%20Iteration.png)

- A block of code will repeat a known number of times.
- For example: a for loop will execute an indented block for each value in a list of values.

### Flow diagram

![Flow diagram](https://image-v2.cdn.app.senecalearning.com/2018-08/05478307-2c1a-477d-a959-b7d2b44b220a/2.2.3%20Iteration.png)

- A flow diagram for iteration uses the diamond shape.

## Test yourself on Iteration

- What are the two types of *iteration*?
- What is **definite** iteration?

[Practise this topic for free](https://app.senecalearning.com/classroom/course/72d0364c-db0a-4630-8e0a-61f48cae0252/section/e6f14a47-ddc5-46d6-bca3-8e32c72f0c32/session)

- Previous topic: [1.6.1 Selection](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-6-1-selection.md)
- Next topic: [2.1.1 Lists](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/2-1-1-lists.md)

## Coding: Introduction to Python v3 contents

### 1 Introduction to Python
- 1.1 Python
  - [1.1.1 Python](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-1-1-python.md)
- 1.2 Input & Output
  - [1.2.1 Input & Output](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-2-1-input-and-output.md)
- 1.3 Data Types
  - [1.3.1 Data Types](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-3-1-data-types.md)
- 1.4 Variables & Constants
  - [1.4.1 Variables & Constants](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-4-1-variables-and-constants.md)
- 1.5 Operators
  - [1.5.1 Arithmetic & Relational Operators](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-5-1-arithmetic-and-relational-operators.md)
  - [1.5.2 Boolean & Assignment Operators 2](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-5-2-boolean-and-assignment-operators-2.md)
- 1.6 Program Flow
  - [1.6.1 Selection](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-6-1-selection.md)
  - [1.6.2 Iteration](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/1-6-2-iteration.md)

### 2 Data Structures
- 2.1 Lists & Strings
  - [2.1.1 Lists](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/2-1-1-lists.md)
  - [2.1.2 Strings](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/2-1-2-strings.md)
- 2.2 File Handling
  - [2.2.1 File Handling](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/2-2-1-file-handling.md)

### 3 Modularity
- 3.1 Subroutines
  - [3.1.1 Subroutines](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/3-1-1-subroutines.md)
- 3.2 Data Flow
  - [3.2.1 Data Flow](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/3-2-1-data-flow.md)

### 4 Good Practice
- 4.1 Naming & Whitespace
  - [4.1.1 Identifiers](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/4-1-1-identifiers.md)
  - [4.1.2 Whitespace](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/4-1-2-whitespace.md)
- 4.2 Comments
  - [4.2.1 Comments](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/4-2-1-comments.md)
- 4.3 Exceptions
  - [4.3.1 Exceptions](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/4-3-1-exceptions.md)