Junior — Middle

In what situations does the default case in a Select statement trigger?

sobes.tech AI

Answer from AI

In Go, the select statement is used to work with multiple channels simultaneously. The default block executes when none of the channels in the select are ready for an operation (neither reading nor writing is possible at the moment).

This allows avoiding blocking the goroutine and executing alternative code immediately.

Example:

select {
case msg := <-ch1:
    fmt.Println("Received message:", msg)
case ch2 <- 42:
    fmt.Println("Sent message to ch2")
default:
    fmt.Println("No channel is ready, executing default")
}

If neither ch1 is ready for reading nor ch2 for writing, the default block will be executed.

Thus, default is useful for non-blocking behavior when working with channels.

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