Concurrent execution model in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a new goroutine that prints "Hello".

Go

go [1]()

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Afmt.Println

BprintHello

Cmain

DhelloWorld

Attempts:

3 left

💡 Hint

Common Mistakes

Using fmt.Println directly after go without parentheses.

Trying to start a goroutine with a variable name instead of a function.

The go keyword starts a new goroutine. You need to call a function name after it. Here, printHello is the function that prints "Hello".

2fill in blank

medium

Complete the code to wait for the goroutine to finish using a channel.

Go

done := make(chan bool)
go func() {
    fmt.Println("Working...")
    done[1]true
}()
<-done

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A<-

B:=

C->

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using assignment = instead of channel send operator.

Using -> which is invalid in Go.

To send a value into a channel, use the <- operator pointing to the channel. Here, done <- true sends true to the done channel.

3fill in blank

hard

Fix the error in the code to correctly launch a goroutine with a parameter.

Go

func printNumber(n int) {
    fmt.Println(n)
}

func main() {
    for i := 1; i <= 3; i++ {
        go printNumber([1])
    }
    time.Sleep(time.Second)
}

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A&i

B3

Ci+1

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the address of i causing all goroutines to print the last value.

Passing a constant instead of the loop variable.

The loop variable i is passed directly to the goroutine function. This captures the current value correctly. Using &i would pass the address, causing all goroutines to print the same value.

4fill in blank

hard

Fill both blanks to create a buffered channel and send two values without blocking.

Go

ch := make(chan int, [1])
ch[2] 1
ch <- 2

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A2

B<-

C=

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using assignment = instead of send operator.

Creating an unbuffered channel which blocks on send.

A buffered channel with capacity 2 allows sending two values without blocking. The send operator <- is used to send values into the channel.

5fill in blank

hard

Fill all three blanks to create a select statement that waits on two channels and prints which one received a value.

Go

select {
case msg1 := <-[1]:
    fmt.Println("Received from", [2], ":", msg1)
case msg2 := <-[3]:
    fmt.Println("Received from", "chan2", ":", msg2)
}

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Achan1

B"chan1"

Cchan2

D"chan2"

Attempts:

3 left

💡 Hint

Common Mistakes

Using channel variables as strings in print statements.

Mixing up channel names and string literals.

The select waits on channels chan1 and chan2. The printed name is a string, so "chan1" is used to show the channel name in output.