Loops Assessment

• Friday, October 4th, 12-4pm, Room 426
• Monday, October 7th, 12-2:30pm, Room 408
• Take your computer and pen
• Part on paper, part on computer

Loops review

• Loops are counters. They count how many times you should run code. You can also use the count as a variable to do something.
  • You can count columns.
  • You can count pixels.
  • You can count indexes.
  • You can count …
• Loop anatomy and syntax: 3 parameters
  1. Where to start: Initialization let i = 0
  2. When to exit: Boolean test i < width
  3. How to get from start to finish: Incrementation operation i++, i+=10

for (let i = 0; i < width; i++) {

}

• When writing code, as soon as you see a pattern in numbers, you can re-write it as a loop.
• for() loops versus draw() loop. Code in for() loops all happen in 1 frame of animation. The draw() loop happens over time.

Worksheet and Assignment review

• Checkerboard (counting columns)

let cols = 10;
let rows = 10;

function setup() {
  createCanvas(400, 400);
}

function draw() {
  background(220);
  for (let r = 0; r < 10; r++) {
    for (let c = 0; c < 10; c++) {
      if (r % 2 == 0 && c % 2 == 0) {
        fill(0);
      } else if (r % 2 == 1 && c % 2 == 1) {
        fill(0);
      } else {
        fill(255);
      }
      rect(
        (c * width) / cols,
        (r * height) / rows,
        width / cols,
        height / rows
      );
    }
  }
}

https://editor.p5js.org/icm-nun/full/5qzKVtgBp

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Test yourself (loops)

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