add

Author: wolfstudy

happens_before/four.go

@@ -0,0 +1,22 @@
+package main
+
+//as above, but with the send and receive statements swapped and using an unbuffered channel
+
+//var cc = make(chan int)
+
+//If the channel were buffered (e.g., c = make(chan int, 1))
+// then the program would not be guaranteed to print "hello, world".
+var cc = make(chan int, 1)
+var aaaa string
+
+func fff() {
+	aaaa = "hello, world"
+	<-cc
+}
+
+//is also guaranteed to print "hello, world".
+func main() {
+	go fff()
+	cc <- 0
+	print(aaaa)
+}