Source: https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/2-2-1-file-handling [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) › File Handling # File Handling Coding: Introduction to Python v3, topic 2.2.1 ## Files Without files we can only store data in the memory. ### Files ![Files](https://image-v2.cdn.app.senecalearning.com/2018-07/4d7e1e31-f726-401e-92ad-d4e7fb3b49b2/File-Transfer-Files-Computer-.jpg) - Files allow us to store data so that it persists even when our program is not running. - This allows programs to 'carry on where they left off' when they are executed. ### Text files ![Text files](https://image-v2.cdn.app.senecalearning.com/2018-08/9cb6dab6-2b93-45ea-920a-64c300699210/Soviet-Constitution-Russian-Writing-.jpg) - Text files consist of string data that can be read and processed by many applications. ### Binary files ![Binary files](https://image-v2.cdn.app.senecalearning.com/2018-07/31c77d00-497e-4e13-9319-bd43c2c1c731/Computer-Binary-1-0-Byte-.jpg) - Binary files consist of binary data that is read and processed by specific applications. ## File Handling We must be careful with the way that we access files so that we do not accidentally corrupt them. ### Open the file ![Open the file](https://image-v2.cdn.app.senecalearning.com/2020-08/c948165c-a8f0-4326-b157-de6e16db9e0d/door-open-entrance-open-door.jpg) - First, we open the file for use, so that the program can read from or write to it. - We can do this using: - open("filename.txt", "r") - open("filename.txt", "w") - Opening with "r" will allow you to read from the file. - Opening with "w" will allow you to write to the file ### Assign the file to a variable ![Assign the file to a variable](https://image-v2.cdn.app.senecalearning.com/2018-09/9e5843e2-42b9-4a41-8fa5-a2bf2240f09d/filing-cabinet-files-.png) - The file must be assigned to a variable so that we can keep referring to it. - This can be done as follows: - myFile = open("filename.txt", "r") - myFile = open("filename.txt", "w") ### Read / write ![Read / write](https://image-v2.cdn.app.senecalearning.com/2018-07/8a85e66f-79f5-4eec-b73c-ce40108d53b6/quran-reading-studying.jpg) - We can now read or write to the file using the following commands: - myFile.readline() will return the next line of a file as a string. - myFile.write() will write a line to the file. ### Close the file ![Close the file](https://image-v2.cdn.app.senecalearning.com/2018-09/9daa7ad5-ad60-409e-984b-4a72612e8502/books.jpg) - Finally, we must close the file so that it is free for another program to access. - We can do this using: - myFile.close() ## Test yourself on File Handling - What does a text file contain? - What is the main reason to use files? - File Handling - Which of these are valid file handling methods? - If we don't use the correct methods to access files, what might happen? [Practise this topic for free](https://app.senecalearning.com/classroom/course/72d0364c-db0a-4630-8e0a-61f48cae0252/section/0fb21293-75c9-4177-8d0a-88c8658f2c61/session) - Previous topic: [2.1.2 Strings](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/2-1-2-strings.md) - Next topic: [3.1.1 Subroutines](https://senecalearning.com/en-gb/revision-notes/gcse/coding/national-curriculum/3-1-1-subroutines.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)