3.1 Variables and Assignments

Enduring Understanding

To find specific solutions to generalizable problems, programmers represent and organize data in multiple ways.

Learning Objective

Represent a value with a variable.

Essential Knowledge

A variable is an abstraction inside a program that can hold a value. Each variable has associated data storage that represents one value at a time, but that value can be a list or other collection that in turn contains multiple values.

Using meaningful variable names helps with the readability of program code and understanding of what values are represented by the variables.

Some programming languages provide types to represent data, which are referenced using variables. These types include numbers, Booleans, lists, and strings.

Some values are better suited to representation using one type of datum rather than another

Learning Objective

Determine the value of a variable as a result of an assignment.

Essential Knowledge

The assignment operator allows a program to change the value represented by a variable.

The exam reference sheet provides the “ ” operator to use for assignment. For example,

Text:

a <-- expression

Block:

evaluates expression and then assigns a copy of the result to the variable a.

The value stored in a variable will be the most recent value assigned. For example:

a <-- 1

b <-- a

a <-- 2

display(b)

still displays 1