Chapter 05 — Loops: for, while, do while

Level: beginner Estimated time: 4 h Prerequisites: Chapter 04 — Conditions (if, else, switch) What you will be able to do by the end: write for, while, and do while loops, control their flow with break and continue, and nest loops to traverse 2D grids.

05.0 — Chapter objectives

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

• understand why loops are necessary;
• repeat an instruction several times;
• use a for loop;
• understand initialization, condition, and increment;
• use a while loop;
• use a do while loop;
• use break;
• use continue;
• create counters;
• iterate over ascending or descending values;
• use a loop with conditions;
• create nested loops;
• avoid infinite loops;
• choose between for, while, and do while;
• prepare for working with lists in the next chapter.

05.1 — Why do we need loops?

Suppose we want to display:

Niveau 1
Niveau 2
Niveau 3
Niveau 4
Niveau 5

We could write:

void main() {
  print('Niveau 1');
  print('Niveau 2');
  print('Niveau 3');
  print('Niveau 4');
  print('Niveau 5');
}