Exercises: Core Basics Review

Let's think about this for a second

This lesson isn't new teaching content - it's meant to help you confidently review the function, slice, map, and loop skills you already learned in the Basic and Intermediate chapters. We recommend writing the code yourself for each task before comparing it against the solution. Finishing this practice set will make the next project chapter a lot smoother to work through. The difficulty is roughly medium, focused mainly on testing slice manipulation and map counting logic.

Exercises

Task 1: Write a sum(nums []int) int function that takes an int slice and returns the sum of all its elements. Task 2: Write a countChars(s string) map[rune]int function that takes a string and counts how many times each character appears, as a map[rune]int. Task 3: Write a filterEven(nums []int) []int function that takes an int slice as a parameter and returns a new slice containing only the even numbers. Task 4: Create a struct Person{Name string; Age int}, then write an oldest(people []Person) Person function that takes a Person slice and finds and returns the person with the highest Age.

• Wrote and test-ran both the sum() and countChars() functions yourself
• filterEven() function correctly filters out only the even numbers
• oldest() function correctly finds the person with the highest Age in the Person slice

Code Example

package main

import "fmt"

// Task 1
func sum(nums []int) int {
	// TODO: implement
	return 0
}

// Task 2
func countChars(s string) map[rune]int {
	// TODO: implement
	return nil
}

// Task 3
func filterEven(nums []int) []int {
	// TODO: implement
	return nil
}

// Task 4
type Person struct {
	Name string
	Age  int
}

func oldest(people []Person) Person {
	// TODO: implement
	return Person{}
}

func main() {
	fmt.Println(sum([]int{1, 2, 3, 4, 5}))
	fmt.Println(countChars("gopher"))
	fmt.Println(filterEven([]int{1, 2, 3, 4, 5, 6}))
	people := []Person{{"Aye", 25}, {"Bo", 30}, {"Cho", 22}}
	fmt.Println(oldest(people))
}

The terminal should show sum() as 15, filterEven() as [2 4 6], and oldest() as {Bo 30} (the countChars output will be a character count map).