package main func main() { c := make(chan int) for range 3 { select { default: println(1) case <-c: println(2) case c <- 1: println(3) } } }

This code has several errors and shortcomings:

1. The for range 3 loop is incorrect because range is used with slices, arrays, strings, channels, or maps, not with numbers. The correct way is to use for i := 0; i < 3; i++.

2. The channel c is created without buffering (make(chan int)), so send and receive operations block if there is no corresponding receiver or sender.

3. In the select statement, there are three cases:

   • default — executes if none of the other cases are ready.
   • case <-c: — attempts to receive from the channel.
   • case c <- 1: — attempts to send to the channel.

Since the channel is unbuffered and no one is reading from it, the attempt to send (c <- 1) will block, and this case will not be selected.

Because no one is sending to the channel, the case <-c: is also not ready.

Thus, each time, the default case will execute, and the program will print 1 three times.

Corrected example:

package main

func main() {
    c := make(chan int)

    for i := 0; i < 3; i++ {
        select {
        default:
            println(1)
        case <-c:
            println(2)
        case c <- 1:
            println(3)
        }
    }
}

The output will be:

1
1
1

If the channel is made buffered, for example make(chan int, 1), then the send case can succeed, and the output will change.