Pointer declaration in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of pointer declaration and dereference

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    var x int = 10
    var p *int = &x
    fmt.Println(*p)
}

A 0

B Memory address of x

C 10

D Compilation error

💡 Hint

Remember that *p gives the value stored at the address p points to.

The pointer p holds the address of x. Using *p accesses the value at that address, which is 10.

❓ Predict Output

intermediate

Pointer declaration with nil value

What will this Go program print?

Go

package main
import "fmt"
func main() {
    var p *int
    if p == nil {
        fmt.Println("Pointer is nil")
    } else {
        fmt.Println("Pointer is not nil")
    }
}

A Runtime panic

B Pointer is not nil

C Compilation error

D Pointer is nil

💡 Hint

Uninitialized pointers have the zero value nil.

The pointer p is declared but not assigned, so it defaults to nil. The if condition detects this and prints accordingly.

❓ Predict Output

advanced

Pointer modification effect

What is the output of this Go program?

Go

package main
import "fmt"
func main() {
    x := 5
    p := &x
    *p = 20
    fmt.Println(x)
}

A 20

B 5

C Compilation error

D Runtime panic

💡 Hint

Changing the value via pointer changes the original variable.

The pointer p points to x. Assigning *p = 20 changes x to 20. So printing x outputs 20.

❓ Predict Output

advanced

Pointer declaration syntax error

Which option will cause a compilation error in Go?

A var p *int = nil

B var p *int = 10

C

var p *int
p = new(int)

D

var x int = 5
var p *int = &x

💡 Hint

A pointer must hold an address or nil, not a direct value.

Option B tries to assign an int value directly to a pointer variable, which is invalid. The others are valid pointer declarations or assignments.

🧠 Conceptual

expert

Pointer zero value and usage

Which statement about pointer declaration in Go is TRUE?

A The zero value of a pointer variable is nil, meaning it points to no valid memory.

B Dereferencing a nil pointer returns zero without error.

C You can assign an integer value directly to a pointer variable.

D A pointer variable declared without initialization points to a random memory location.

💡 Hint

Think about what happens when you declare a pointer but don't assign it.

In Go, uninitialized pointers have the zero value nil, which means they don't point to any valid memory. Dereferencing nil causes a runtime panic.