Introduction to Subroutines (AQA GCSE Computer Science)

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Introduction to Subroutines

What is a subroutine? 

  • Subroutines are an out of line block of code that may be called by simply writing their name in a program     

  • Subroutines are given a unique name so they can be called anywhere in a program

  • There are many benefits to using subroutines, these include

    • Making bigger problems easier to break down (decompose) and code

    • Allows team members to be able to work on different parts of a problem

    • Makes the program easier to debug

    • Makes programs more efficient as code is not duplicated

  • More detailed information about subroutines can be found in the 'Structured Programming' section

Meaningful Identifiers

What are meaningful identifiers?

  • Meaningful identifiers are sensible names used for variables, constants or subroutines

  • A meaningful identifier must be used to help aid the maintainability of a program

  • An example would be a variable used for an input of a users' first name

Meaningful Identifier

Poor Identifier

name ← USERINPUT

IF name == "Mike" THEN

cost ← 100 * 0.5

ELSE

OUTPUT name + " your total is: " + cost

a ← USERINPUT

IF a == "Mike" THEN

b ← 100 * 0.5

ELSE

OUTPUT a + " your total is: " + b

Examples of using subroutines

Prgm_Introduction to Subroutines

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