Why does this code only print 10?

<p>I am new to go, and I am trying to understand how goroutines work. I don&#39;t understand the following code. It only prints &#39;10&#39;. I thought go was pass by value? What exactly is going on with defer and wait in this case?</p> <p>Also what is the difference in the order in which defer is called? Does it not make a difference? Are the following the same?</p> <pre><code> defer wg.Done() fmt.Println(i) fmt.Println(i) defer wg.Done() </code></pre> <p><a href="https://play.golang.org/p/T0_Q8HHF0E" rel="nofollow">https://play.golang.org/p/T0_Q8HHF0E</a></p> <hr/>**评论：**<br/><br/>Logiraptorr: <pre><p>Go is pass by value, this issue with the code you linked is that the value here is the address of i. For loops in Go reuse the same memory for each loop iteration, so all go routines created in the loop are referring to the same address. When they all execute (after the loop has finished), i is 10. See <a href="https://github.com/golang/go/wiki/CommonMistakes#using-goroutines-on-loop-iterator-variables" rel="nofollow">here</a> for more information.</p></pre>phat4life: <pre><p>awesome thanks</p></pre>antonmry: <pre><p>you may try something like <a href="https://play.golang.org/p/oZn2Oy_jMq" rel="nofollow">https://play.golang.org/p/oZn2Oy_jMq</a></p></pre>