 # Animal Magic Learning Exercise

## Introduction

Package math/rand provides support for generating pseudo-random numbers.

Here is how to generate a random integer between `0` and `99`:

``````n := rand.Intn(100) // n is a random int, 0 <= n < 100
``````

Function `rand.Float64` returns a random floating point number between `0.0` and `1.0`:

``````f := rand.Float64() // f is a random float64, 0.0 <= f < 1.0
``````

There is also support for shuffling a slice (or other data structures):

``````x := []string{"a", "b", "c", "d", "e"}
// shuffling the slice put its elements into a random order
rand.Shuffle(len(x), func(i, j int) {
x[i], x[j] = x[j], x[i]
})
``````

### Seeds

The number sequences generated by package `math/rand` are not truly random.
They are completely determined by an initial `seed` value. By default, the package uses the integer `1` as a seed.

In order to get a different sequence of random numbers, we need to specify a different seed value. A simple approach is to use the "current time":

``````rand.Seed(time.Now().UnixNano())
``````

Setting the seed must be done before calling any of the functions that generate random numbers. We usually only need to set the seed once in our program. From one seed we can generate many random numbers.

#### Warning

If you don't call `rand.Seed`, then the package will produce the same sequence of random numbers each time your program runs!

## Instructions

Elaine is working on a new children's game that features animals and magic wands. It is time to code functions for rolling a die, generating random wand energy and shuffling a slice.

### 1. Seed the random number generator.

Implement a `SeedWithTime` function that seeds the `math.rand` package with the current computer time.

### 2. Roll a die.

Implement a `RollADie` function.

This will be the traditional twenty-sided die with numbers 1 to 20.

``````d := RollADie() // d will be assigned a random int, 1 <= d <= 20
``````

### 3. Generate wand energy.

Implement a `GenerateWandEnergy` function. The wand energy should be a random floating point number between 0.0 and 12.0.

``````f := GenerateWandEnergy()  // f will be assigned a random float64, 0.0 <= f < 12.0
``````

### 4. Shuffle a slice.

The game features eight different animals:

• ant
• beaver
• cat
• dog
• elephant
• fox
• giraffe
• hedgehog

Write a function `ShuffleAnimals` that returns a slice with the eight animals in random order.

Last updated 31 May 2023 Edit via GitHub    