Fundamental Components of Programs (Edexcel GCSE Computer Science)

Constants, Variables, Initialisation & Assignment

Constants

• A constant is an identifier set once in the lifetime of a program

• Constants are named in all uppercase characters

• Constants aid the readability and maintainability

• If a constant needs to be changed, it should only need to be altered in one place in the whole program

Variables

• A variable is an identifier that can change in the lifetime of a program

• Variables are named in lowercase characters unless combining multiple words

• A variable can be associated a datatype when it is declared

• When a variable is declared, memory is allocated based on the data type indicated

Initialisation & assignment

• A variable can be initialised with a value

• The assignment operator = is used to set or change the value of a variable

Inputs & Outputs

Inputs

• The input() function is used to capture an input from the user

• All inputs default to strings and may need converting to the required data type in the program

Outputs

• The print() function is used to output to the screen

• An output can be formatted to the users needs using string formatting {}