Variables & Data

Variables are labeled boxes

A variable is a named place where the computer remembers something.

Think of a box with a label on it. The label is the variable name. The thing inside the box is its value. You can look at the value later, or replace it with a new one.

• Name the information.
• Store a value.
• Use the name later.
• Change the value when the program needs to.

Describe the logic before the syntax

Our pseudocode says exactly what we want the program to do without choosing a programming language yet.

CREATE playerName AS "Brian"
CREATE score AS 0

CHANGE score TO 10

SHOW playerName
SHOW score

The same idea in Python

Python uses = for both the first assignment and later reassignment. The variable names still play the same role as they did in pseudocode.

playerName = "Brian"
score = 0

score = 10

print(playerName)
print(score)

The same idea in JavaScript

JavaScript can create variables with let when their values may change. Semicolons are syntax; the underlying logic is unchanged.

let playerName = "Brian";
let score = 0;

score = 10;

console.log(playerName);
console.log(score);

The same idea in C#

C# normally declares the type of data the variable stores. string holds text and int holds whole numbers.

string playerName = "Brian";
int score = 0;

score = 10;

Console.WriteLine(playerName);
Console.WriteLine(score);

The same idea in Java

Java also declares variable types. The program still creates two names, changes score, and displays both values.

String playerName = "Brian";
int score = 0;

score = 10;

System.out.println(playerName);
System.out.println(score);

The same idea in C++

C++ uses typed variables as well. std::cout is simply this language's way to SHOW a value.

std::string playerName = "Brian";
int score = 0;

score = 10;

std::cout << playerName << '\n';
std::cout << score << '\n';