Receive or fetch multiple return values from a goroutine in Go(Golang)

Channels can be used to fetch return value from a goroutine. Channels provide synchronization and communication between goroutines. You can send the return value to a channel in the goroutine and then collect that value in the main function.

To receive multiple values we can create a custom struct type with fields for both return values, then create a channel of that type.

Let’s see a program

package main

import (
	"fmt"
	"time"
)

type result struct {
	sumValue      int
	multiplyValue int
}

func main() {
	resultChan := make(chan result, 1)
	sumAndMultiply(2, 3, resultChan)

	res := <-resultChan
	fmt.Printf("Sum Value: %d\n", res.sumValue)
	fmt.Printf("Multiply Value: %d\n", res.multiplyValue)
	close(resultChan)

}

func sumAndMultiply(a, b int, resultChan chan result) {
	sumValue := a + b
	multiplyValue := a * b
	res := result{sumValue: sumValue, multiplyValue: multiplyValue}
	time.Sleep(time.Second * 2)
	resultChan <- res
	return
}

Output

Sum Value: 5
Multiply Value: 6

In the above program we created a struct named result which has two fields

sumValue

multiplyValue

We then created a variable resultChan which is a channel of length 1 holding value of result struct type. We passed this channel to the sumAndMultiply function. The sumAndMultiply function pushes the resultant struct to the resultChan

res := result{sumValue: sumValue, multiplyValue: multiplyValue}
resultChan <- res

Then in the main function we are waiting on the channel to collect the result

res := <-resultChan

This line will wait until a value is pushed to the resultChan channel.

golang