Best practices in Go - Mini Project: Build & Apply

Best practices in Go programming

📖 Scenario: You are working on a small Go program that calculates the total price of items in a shopping cart. You want to write clean, readable, and maintainable code following Go best practices.

🎯 Goal: Build a Go program that defines a map of items with their prices, calculates the total price using a loop, and prints the result. You will apply best practices such as clear variable naming, proper indentation, and concise code.

📋 What You'll Learn

Create a map named items with string keys and float64 values

Create a variable named total to hold the sum of prices

Use a for loop with variables item and price to iterate over items

Add each price to total

Print the total price with a clear message

💡 Why This Matters

🌍 Real World

Calculating totals from a list of products and prices is common in shopping cart applications and billing systems.

💼 Career

Understanding maps, loops, and formatted output is essential for Go developers working on backend services, e-commerce platforms, and data processing.

1

Create the items map

Create a map called items with these exact entries: "apple": 0.99, "banana": 0.59, "orange": 1.29

Go

# Create the items map with prices
# Your code here

Hint

Use map[string]float64 to create a map with string keys and float64 values.

2

Add a total variable

Create a variable called total of type float64 and set it to 0

Go

package main

func main() {
    items := map[string]float64{"apple": 0.99, "banana": 0.59, "orange": 1.29}
    // Create total variable
    // Your code here
}

Hint

Use var total float64 = 0 to declare the variable.

3

Calculate the total price

Use a for loop with variables item and price to iterate over items. Add each price to total

Go

package main

func main() {
    items := map[string]float64{"apple": 0.99, "banana": 0.59, "orange": 1.29}
    var total float64 = 0
    // Loop over items and add prices to total
    // Your code here
}

Hint

Use for item, price := range items to loop over the map.

4

Print the total price

Write fmt.Printf to print the message Total price: $ followed by the value of total with two decimal places

Go

package main

import "fmt"

func main() {
    items := map[string]float64{"apple": 0.99, "banana": 0.59, "orange": 1.29}
    var total float64 = 0
    for item, price := range items {
        total += price
    }
    // Print the total price
    // Your code here
}

Hint

Use fmt.Printf("Total price: $%.2f\n", total) to format the output with two decimals.

Practice

1. Which of the following is a best practice when naming variables in Go?

easy

A. Use clear and descriptive names that explain the variable's purpose

B. Use single letters for all variable names to save space

C. Use names with special characters to make them unique

D. Use very long names with unnecessary details

Solution

1. Step 1: Understand variable naming importance

   Clear and descriptive names help others understand what the variable holds.

2. Step 2: Evaluate each option

   Using single letters or special characters makes code confusing. Very long names are hard to read.

3. Final Answer:

   Use clear and descriptive names that explain the variable's purpose -> Option A

4. Quick Check:

   Clear names improve readability [OK]

Hint: Pick option promoting clarity and readability [OK]

Common Mistakes:

• Choosing short, unclear variable names
• Using special characters in names
• Making names unnecessarily long

2. Which of the following Go code snippets correctly handles an error returned by a function?

easy

A. result, err := doSomething()
if err = nil {
fmt.Println("Error occurred")
}

B. result, err := doSomething()
if err == nil {
fmt.Println("Error occurred")
}

C. result, err := doSomething()
if err != nil {
fmt.Println("Error occurred")
}

D. result, _ := doSomething()
fmt.Println(result)

Solution

1. Step 1: Identify correct error check syntax

   In Go, errors are checked with 'if err != nil' to detect an error.

2. Step 2: Check each option's error handling

   result, err := doSomething() if err != nil { fmt.Println("Error occurred") } prints an error message when err is not nil, which is correct. result, err := doSomething() if err == nil { fmt.Println("Error occurred") } checks err == nil incorrectly. result, err := doSomething() if err = nil { fmt.Println("Error occurred") } uses assignment '=' instead of comparison '=='. result, _ := doSomething() fmt.Println(result) ignores the error by using _ and prints the result anyway, which is incorrect.

3. Final Answer:

   result, err := doSomething() if err != nil { fmt.Println("Error occurred") } -> Option C

4. Quick Check:

   Check error with 'err != nil' [OK]

Hint: Remember: error check is 'if err != nil' [OK]

Common Mistakes:

• Using '=' instead of '==' in conditions
• Checking 'err == nil' to detect errors
• Ignoring errors without handling

3. What will be the output of the following Go code?

package main
import "fmt"
func main() {
    nums := []int{1, 2, 3}
    sum := 0
    for _, n := range nums {
        sum += n
    }
    fmt.Println(sum)
}

medium

A. 6

B. 123

C. 0

D. Error

Solution

1. Step 1: Understand the loop and sum calculation

   The loop goes through each number in nums: 1, 2, 3 and adds them to sum.

2. Step 2: Calculate the sum

   sum = 0 + 1 + 2 + 3 = 6

3. Final Answer:

   6 -> Option A

4. Quick Check:

   Sum of [1,2,3] = 6 [OK]

Hint: Sum elements by adding each in the loop [OK]

Common Mistakes:

• Concatenating numbers as strings
• Starting sum from wrong initial value
• Misunderstanding range loop syntax

4. Identify the error in the following Go code snippet and choose the best fix:

func divide(a, b int) int {
    return a / b
}

func main() {
    result := divide(10, 0)
    fmt.Println(result)
}

medium

A. Change function to return float64 instead of int

B. Add error handling to check if b is zero before dividing

C. Remove the divide function and do division inline

D. Ignore the error since Go handles division by zero automatically

Solution

1. Step 1: Identify the problem with division by zero

   Dividing by zero causes a runtime panic in Go, which must be prevented.

2. Step 2: Choose the fix that prevents panic

   Adding error handling to check if b is zero before dividing avoids the panic. Changing return type or removing function does not fix the error. Go does not handle division by zero automatically.

3. Final Answer:

   Add error handling to check if b is zero before dividing -> Option B

4. Quick Check:

   Prevent division by zero [OK]

Hint: Always check divisor before dividing to avoid panic [OK]

Common Mistakes:

• Ignoring division by zero errors
• Assuming Go handles zero division safely
• Changing return type without fixing logic

5. You want to write a Go function that returns a map of words to their counts from a slice of strings. Which approach follows best practices for clarity, error handling, and simplicity?

hard

A. Use nested loops to count words multiple times for accuracy

B. Use global variables to store counts and update them inside the function

C. Return a pointer to the map and panic if input slice is empty

D. Use a simple loop to count words, return the map, and handle empty input gracefully

Solution

1. Step 1: Understand best practices for function design

   Functions should be simple, clear, and handle edge cases like empty input without panicking.

2. Step 2: Evaluate each option

   Use a simple loop to count words, return the map, and handle empty input gracefully uses a simple loop and handles empty input gracefully, which is best practice. Use nested loops to count words multiple times for accuracy is inefficient with nested loops. Return a pointer to the map and panic if input slice is empty uses panic and pointers unnecessarily. Use global variables to store counts and update them inside the function uses global variables, which reduces clarity and safety.

3. Final Answer:

   Use a simple loop to count words, return the map, and handle empty input gracefully -> Option D

4. Quick Check:

   Simple, clear, safe function [OK]

Hint: Keep functions simple and handle edge cases safely [OK]

Common Mistakes:

• Using complex nested loops unnecessarily
• Panicking instead of returning errors
• Using global variables inside functions