```
import (
"fmt"
)
func main() {
AlterPrint()
}
// POINT: communicate between goroutines by channel
func AlterPrint(){
letter, number := make(chan bool), make(chan bool)
letterDone := make(chan bool)
numberDone := make(chan bool)
go func() {
i := 1
for {
if i > 28 {
numberDone <- true
return
}
select{
case <-number: {
fmt.Print(i)
i++
fmt.Print(i)
i++
letter <- true
break
}
default: {
break
}
}
}
}()
go func(){
i := 'A'
for {
if i > 'Z' {
letterDone <- true
return
}
select{
case <-letter: {
fmt.Print(string(i))
i++
fmt.Print(string(i))
i++
number <- true
break
}
default: {
break
}
}
}
}()
number <- true
<- letterDone
<- numberDone
}
```
I expect the output of "12AB34CD56EF78GH910IJ1112KL1314MN1516OP1718QR1920ST2122UV2324WX2526YZ2728",
but the actual output is
```
goroutine 1 [chan receive]:
main.AlterPrint()
/tmp/54841538.go:66 +0x183
main.main()
/tmp/54841538.go:7 +0x14
goroutine 5 [chan send]:
main.AlterPrint.func1(0xc82000c240, 0xc82000c180, 0xc82000c120)
/tmp/54841538.go:31 +0x25a
created by main.AlterPrint
/tmp/54841538.go:40 +0xde
exit status 2
```
有疑问加站长微信联系（非本文作者）
