Creating struct values in Go - Practice Exercises

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of struct literal with field names

What is the output of this Go program?

Go

package main
import "fmt"
type Person struct {
    Name string
    Age  int
}
func main() {
    p := Person{Name: "Alice", Age: 30}
    fmt.Println(p)
}

A {Name: Alice, Age: 30}

B {Alice 30}

C Person{Name: "Alice", Age: 30}

D {Name:Alice Age:30}

💡 Hint

Look at how fmt.Println prints structs by default.

In Go, fmt.Println prints struct values without field names, just the values in order inside braces.

❓ Predict Output

intermediate

Output of struct literal without field names

What is the output of this Go program?

Go

package main
import "fmt"
type Point struct {
    X int
    Y int
}
func main() {
    p := Point{10, 20}
    fmt.Println(p)
}

A Point{10, 20}

B {X=10, Y=20}

C {10 20}

D {X:10 Y:20}

💡 Hint

Struct literals can omit field names if values are in order.

When printing, fmt.Println shows struct fields as values in braces without field names.

❓ Predict Output

advanced

Output of nested struct values

What is the output of this Go program?

Go

package main
import "fmt"
type Address struct {
    City  string
    State string
}
type User struct {
    Name    string
    Address Address
}
func main() {
    u := User{Name: "Bob", Address: Address{City: "NY", State: "NY"}}
    fmt.Println(u)
}

A User{Name: "Bob", Address: Address{City: "NY", State: "NY"}}

B {Name:Bob Address:{City:NY State:NY}}

C {Bob {City:NY State:NY}}

D {Bob {NY NY}}

💡 Hint

fmt.Println prints nested structs recursively without field names.

fmt.Println prints nested structs showing values inside braces without field names.

❓ Predict Output

advanced

Output of pointer to struct literal

What is the output of this Go program?

Go

package main
import "fmt"
type Car struct {
    Brand string
    Year  int
}
func main() {
    c := &Car{Brand: "Tesla", Year: 2022}
    fmt.Println(*c)
}

A {Tesla 2022}

B &{Tesla 2022}

C {Brand:Tesla Year:2022}

D Car{Brand: "Tesla", Year: 2022}

💡 Hint

Dereferencing pointer prints the struct value.

Dereferencing the pointer with *c gives the struct value, printed without field names.

🧠 Conceptual

expert

Number of fields in struct literal with embedded struct

Given the structs below, how many fields does the struct literal have when creating a value of type Employee?

Go

type Person struct {
    Name string
    Age  int
}
type Employee struct {
    Person
    ID int
}

// Creating value:
// e := Employee{Person{Name: "Eve", Age: 28}, 101}

A 2 fields: Person and ID

B 3 fields: Name, Age, and ID

C 1 field: ID only

D 4 fields: Person, Name, Age, and ID

💡 Hint

Embedded structs count as one field in the outer struct literal.

Employee struct has two fields: an embedded Person struct and an int ID. The literal uses two values.