Numbers

Wirescript has two kinds of number. An int is a whole number. A float is a number that can have a fraction, like 2.5. Both are 64-bit, which means an int can go up to 9,223,372,036,854,775,807, and a float can hold very large and very small numbers. This lesson is about what happens when you divide them.

Contents

• Code
• Run
• Under the Hood
• Modify
• Make
• Good to Know

button1 Held -> chip addPizza
button2 Held -> chip addPerson
chip text -> decal Text

Code

@left in addPizza: exec
@left in addPerson: exec
var pizzas: int = 0
var people: int = 0
let slices = pizzas.Value * 8
let each = slices / people.Value
let spare = slices % people.Value
@right out text = "${slices} slices, ${people.Value} people: ${each} each, ${spare} spare"

on addPizza {
  pizzas += 1
}

on addPerson {
  people += 1
}

Each pizza has 8 slices, shared between everyone. * multiplies. / divides, and an int divided by an int gives an int: the remainder is dropped, so 7 / 2 is 3. % gives the remainder that / dropped, so 7 % 2 is 1.

With 2 pizzas and 3 people, how many slices does each person get, and how many are spare? What does the sign say with 1 pizza and nobody there yet?

Run

1. Compile the chip and paste it in-game. Place two Buttons and a brick with a Text Decal.
2. Wire the Buttons’ Held outputs to addPizza and addPerson, and text to the Text Decal’s Text.
3. Add one pizza before anyone arrives. The sign reads “8 slices, 0 people: 0 each, 0 spare”. Dividing by zero gives 0, not an error.
4. Add 3 people and another pizza: “16 slices, 3 people: 5 each, 1 spare”.

Under the Hood

Open the chip. There is one Multiply, one Divide and one Modulo gate, all pure, wired from the two Variable gates. Divide and Modulo both take slices and people, so they always agree with each other.

A number written with a point, like 8.0, is a float. Without one, like 8, it is an int. When one side of +, -, *, / or % is a float, the result is a float and keeps its fraction: 7.0 / 2 is 3.5.

Modify

1. Show the exact share in pizzas. as float turns a value into a float before the divide:

   @left in addPizza: exec
   @left in addPerson: exec
   var pizzas: int = 0
   var people: int = 0
   let share = pizzas.Value as float / people.Value
   @right out text = "Each person gets ${share} pizzas"
   
   on addPizza {
     pizzas += 1
   }
   
   on addPerson {
     people += 1
   }
   

   as applies before the /, so this is (pizzas as float) / people. With 2 pizzas and 4 people, each person now gets half a pizza instead of 0.

2. Order enough pizza. Everyone wants 3 slices, and pizzas come whole. Show how many to buy: (people.Value * 3 + 7) / 8. Adding 7 before dividing by 8 rounds up instead of down. Try it with 1, 3 and 8 people.

3. Take a square root of a number that goes negative:

   @left in down: exec
   var level: float = 4.0
   @right out text = "sqrt(${level.Value}) = ${sqrt(level.Value)}"
   
   on down {
     level -= 2.0
   }
   

   The first press shows the root of 2. The second shows the root of 0. The third asks for the root of -2, which has no answer as a real number: the sign shows 0.

Make

Make a stopwatch. While a Switch is on, a Clock adds one to an int every tenth of a second (on Clock(interval = 0.1, enabled = running)). The sign shows the time as seconds and tenths, like “12.3 s”, using / and % on the int. A Button sets it back to 0.

switch Enabled -> chip running
button Held -> chip reset
chip text -> decal Text

Good to Know

• Dividing by zero, or taking the remainder by zero, gives 0.
• A result that is not a real number, such as the square root of a negative number, or one too large for a float, is read as 0 by the gate it goes into.

Next: True and False.