Chapter 04 — Conditions: if, else if, else, switch

Level: beginner Estimated time: 3 h Prerequisites: Chapter 03 — Operators and Expressions What you will be able to do by the end: make a program react to data using if, else if, else, and switch, including Dart's modern switch expression.

04.0 — Chapter Objectives

By the end of this chapter, you will be able to:

• understand what a condition is;
• use if;
• use else;
• use else if;
• combine multiple conditions;
• create nested conditions;
• use logical operators in a condition;
• use switch;
• understand when to use if or switch;
• build decision systems;
• build simple game logic;
• display a Game Over;
• handle different levels;
• award rewards;
• control access to certain features.

04.1 — Why Do We Need Conditions?

So far, our programs have executed instructions in order.

Example:

void main() {
  print('Début');
  print('Joueur');
  print('Fin');
}

The program always runs:

Début
Joueur
Fin

But in a real application, we need to make decisions.

For example:

IF the player still has lives
    continue the game

ELSE
    display Game Over