Function parameters in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of function with multiple parameters

What is the output of this Go program?

Go

package main
import "fmt"
func addMultiply(a int, b int) (int, int) {
    return a + b, a * b
}
func main() {
    sum, product := addMultiply(3, 4)
    fmt.Println(sum, product)
}

A 7 7

B 12 7

C 7 12

D 34 12

💡 Hint

Look at the order of return values and how they are assigned.

The function returns sum first (3+4=7) and then product (3*4=12). The variables sum and product receive these values in order.

❓ Predict Output

intermediate

Output of function with variadic parameter

What does this Go program print?

Go

package main
import "fmt"
func sumAll(nums ...int) int {
    total := 0
    for _, n := range nums {
        total += n
    }
    return total
}
func main() {
    fmt.Println(sumAll(1, 2, 3, 4))
}

A 10

B 24

C Error: variadic parameter not supported

D 1234

💡 Hint

Variadic parameters allow passing any number of arguments.

The function sums all numbers: 1+2+3+4 = 10.

❓ Predict Output

advanced

Output of function with pointer parameter

What is printed by this Go program?

Go

package main
import "fmt"
func increment(x *int) {
    *x = *x + 1
}
func main() {
    a := 5
    increment(&a)
    fmt.Println(a)
}

A Compilation error

B 5

C 0

D 6

💡 Hint

The function changes the value at the pointer's address.

The function increments the value pointed by x, so a changes from 5 to 6.

❓ Predict Output

advanced

Output of function with named return parameters

What does this Go program print?

Go

package main
import "fmt"
func divide(dividend, divisor int) (result int, err string) {
    if divisor == 0 {
        err = "division by zero"
        return
    }
    result = dividend / divisor
    return
}
func main() {
    res, err := divide(10, 0)
    fmt.Println(res, err)
}

A 0

B 0 division by zero

C 10 division by zero

D runtime error: integer divide by zero

💡 Hint

Named return parameters are zero-valued if not set explicitly.

When divisor is zero, err is set but result remains zero (default int). So output is '0 division by zero'.

🧠 Conceptual

expert

Function parameter passing behavior

Which statement correctly describes how Go passes function parameters?

A Go passes parameters by value, but slices and maps behave like references.

B Go passes parameters by reference, so changes affect the caller's variables.

C Go always passes parameters by value, copying the data.

D Go uses pointers automatically for all parameters to optimize performance.

💡 Hint

Think about how slices and maps behave differently from basic types.

Go passes all parameters by value (copy). However, slices and maps contain pointers internally, so changes to their elements affect the original data.