发射所有goroutine后如何使用goroutine按顺序打印数字

Question

How to print numbers in order using goroutine after all goroutines bing emited?

Here is the code which print numbers in random:

func main() {

    var wg sync.WaitGroup
    wg.Add(10)
    for i := 1; i <= 10; i++ {
        go func(i int) {
            defer wg.Done()
            fmt.Printf("i = %d\n", i)
        }(i)
    }
    wg.Wait()

Emit goroutines in order to print numbers like below, it's not the solution I want.

func main() {

    var wg sync.WaitGroup

    for i := 1; i <= 10; i++ {
        wg.Add(1)
        go func(i int) {
            defer wg.Done()
            fmt.Printf("i = %d\n", i)
        }(i)
        wg.Wait()
    }

I want all goroutines being emited, and after then make them print numbers in order.

Answer 1

func main() {
    wg.Add(10)
    count := 10
    cBegins := make([]chan interface{}, count)
    for i := range cBegins {
        cBegins[i] = make(chan interface{})
    }
    go func() {
        cBegins[0] <- struct {}{}
    }()
    for i := 0; i < count; i++ {
        go func(i int) {
            defer wg.Done()
            <-cBegins[i]
            fmt.Printf("i = %d\n", i)
            if i < 9 {
                cBegins[i+1] <- struct {}{}
            }
        }(i)
    }

    wg.Wait()

}