Why structs are used in Go - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a struct named Person.

Go

type Person [1] {
    Name string
    Age  int
}

Drag options to blanks, or click blank then click option'

Astruct

Bclass

Cinterface

Dpackage

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'class' instead of 'struct' because Go does not have classes.

Using 'interface' which is for behavior, not data grouping.

In Go, struct is used to define a new data type that groups fields.

2fill in blank

medium

Complete the code to create a variable of type Person.

Go

var p [1] Person

Drag options to blanks, or click blank then click option'

A=

Bnew

Cvar

D:=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' without declaration.

Using 'var' keyword incorrectly here.

The short declaration operator := is used to declare and initialize variables in Go.

3fill in blank

hard

Fix the error in the code to access the Age field of a Person struct.

Go

fmt.Println(p[1]Age)

Drag options to blanks, or click blank then click option'

A.

B->

C::

D#

Attempts:

3 left

💡 Hint

Common Mistakes

Using '->' which is from other languages like C.

Using '::' or '#' which are invalid in Go for field access.

In Go, the dot . operator is used to access fields of a struct.

4fill in blank

hard

Complete the code to create a struct literal for Person with Name "Alice" and Age 30.

Go

p := Person{Name: "Alice", [1]: 30}

Drag options to blanks, or click blank then click option'

A{

BAge

C}

D[

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets instead of braces.

Omitting the field name for the second value.

Struct literals use curly braces {} and field names to assign values.

5fill in blank

hard

Fill all three blanks to define a struct, create a variable, and assign a value.

Go

type [1] struct {
    Name string
}

var p [2] [3]

Drag options to blanks, or click blank then click option'

APerson

Bp

DPerson{}

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable name as the type.

Not assigning a struct literal when declaring the variable.

First, define the struct type. Then declare a variable of that type and assign a struct literal.

Practice

1. Why do Go programmers use structs in their code?

easy

A. To group related data together into one unit

B. To perform mathematical calculations faster

C. To create loops and control program flow

D. To handle errors automatically

Solution

1. Step 1: Understand the purpose of structs

   Structs are used to combine multiple pieces of related data into a single unit, like grouping a person's name, age, and address together.

2. Step 2: Compare options with struct purpose

   Only To group related data together into one unit describes grouping related data, which matches the purpose of structs. Other options describe unrelated tasks.

3. Final Answer:

   To group related data together into one unit -> Option A

4. Quick Check:

   Structs = Group related data [OK]

Hint: Structs bundle related info like a folder [OK]

Common Mistakes:

• Thinking structs are for calculations
• Confusing structs with loops
• Assuming structs handle errors

2. Which of the following is the correct way to define a struct named Person with fields Name (string) and Age (int) in Go?

easy

A. struct Person { Name: string, Age: int }

B. type Person struct { Name string; Age int }

C. Person := struct(Name string, Age int)

D. class Person { Name string; Age int }

Solution

1. Step 1: Recall Go struct syntax

   In Go, structs are defined using the keyword type followed by the struct name and the struct keyword with fields inside curly braces.

2. Step 2: Check each option

   type Person struct { Name string; Age int } matches Go syntax exactly. Options A and C use incorrect syntax, and D uses 'class' which is not used in Go.

3. Final Answer:

   type Person struct { Name string; Age int } -> Option B

4. Quick Check:

   Go struct syntax = type Person struct { Name string; Age int } [OK]

Hint: Use 'type Name struct { fields }' to define structs [OK]

Common Mistakes:

• Using 'class' instead of 'struct'
• Incorrect field syntax with colons
• Assigning struct with ':=' instead of type

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

package main
import "fmt"

type Book struct {
    Title string
    Pages int
}

func main() {
    b := Book{Title: "Go Basics", Pages: 150}
    fmt.Println(b.Title)
}

medium

A. {Go Basics 150}

B. 150

C. Go Basics

D. Compilation error

Solution

1. Step 1: Understand struct initialization and field access

   The struct Book is created with Title "Go Basics" and Pages 150. Accessing b.Title prints the Title field.

2. Step 2: Identify printed value

   The code prints only b.Title, so output is "Go Basics". Other options print Pages, whole struct, or error which do not match.

3. Final Answer:

   Go Basics -> Option C

4. Quick Check:

   Print struct field = Title value [OK]

Hint: Print struct.field to get that value [OK]

Common Mistakes:

• Printing whole struct instead of field
• Confusing field names
• Expecting Pages to print

4. Identify the error in this Go code that uses a struct:

package main
import "fmt"

type Car struct {
    Brand string
    Year int
}

func main() {
    c := Car{Brand: "Toyota", Year: "2020"}
    fmt.Println(c)
}

medium

A. Year field has wrong data type

B. Missing semicolon after struct definition

C. Cannot print struct directly

D. Brand field name is invalid

Solution

1. Step 1: Check struct field types and values

   The struct defines Year as int, but the code assigns a string "2020" to Year, causing a type mismatch.

2. Step 2: Verify other options

   Go does not require semicolons after struct definitions, structs can be printed, and Brand is a valid field name.

3. Final Answer:

   Year field has wrong data type -> Option A

4. Quick Check:

   Field type mismatch = Year field has wrong data type [OK]

Hint: Match field types exactly when assigning values [OK]

Common Mistakes:

• Assigning string to int field
• Thinking semicolons are needed
• Believing structs can't be printed

5. You want to store information about multiple students, each with a Name (string) and Grades (slice of int). Which approach best uses structs to organize this data?

hard

A. Store all names and grades in a single string separated by commas

B. Use two separate slices: one for names and one for grades, matching indexes

C. Create a map with student names as keys and grades as values

D. Create a struct Student with fields Name string and Grades []int, then make a slice of Student

Solution

1. Step 1: Understand data grouping needs

   Each student has a name and multiple grades, so grouping these related data in one struct is clear and organized.

2. Step 2: Evaluate options for clarity and maintainability

   Create a struct Student with fields Name string and Grades []int, then make a slice of Student uses a struct to group data and a slice to hold many students, which is clean and easy to manage. Other options separate data or mix types, making code harder to maintain.

3. Final Answer:

   Create a struct Student with fields Name string and Grades []int, then make a slice of Student -> Option D

4. Quick Check:

   Structs group related data + slice holds many [OK]

Hint: Use struct for one item, slice for many [OK]

Common Mistakes:

• Using separate slices causing index errors
• Storing data as plain strings
• Using maps without struct grouping