[Beginner] What is the difference between passing an slice containing the address pointer of a struct vs a slice containing the struct to a function

<p>Consider the following <a href="https://play.golang.org/p/VdSJYwvjFV" rel="nofollow">playground</a></p> <p>We see that passing <code>[]*Vertex</code> and <code>[]Vertex</code> both change the underlying struct in the slice.</p> <p>Is both <code>[]*Vertex</code> and <code>[]Vertex</code> storing the vertex&#39;s address?</p> <hr/>**评论：**<br/><br/>YEPHENAS: <pre><p>A slice is a struct consisting of a pointer to an array, a length and a capacity.</p> <pre><code>// []Vertex m = {*,len,cap} // This part gets copied on function call | | +--&gt;[Vertex,Vertex,Vertex,Vertex] // This part does not get copied // []*Vertex k = {*,len,cap} // This part gets copied on function call | | +--&gt;[*,*,*,*] // This part does not get copied | | | | | | | +--&gt;Vertex | | +--&gt;Vertex | +--&gt;Vertex +--&gt;Vertex </code></pre> <p>Slices are not arrays, they point to arrays. This is an array:</p> <pre><code>// [4]Vertex a = [Vertex,Vertex,Vertex,Vertex] // This part gets copied on function call </code></pre></pre>a_k_w: <pre><p>Go is pass by value. So when you pass a type to a function, you are passing the value, which is then copied. When you pass a pointer-type to a function it is also copied. All values are copied. pointer-types are special in that you can use these types to pass state into and out of a function. then the pointer-type can be dereferenced into a type.</p> <p>so in the example, you have a slice of two different types. one slice holds values of pointer-type *Vertex and the other holds values of type Vertex. You also pass the different slices into functions differently. one you are passing the pointer to a slice, and the other you are passing the slice(which is a struct containing three words: len, cap, pointer).</p> <p>So to answer the question. No. The []*Vertex slice is holding pointer-type *Vertex and the []Vertex slice is holding type Vertex.</p> <p>Drop your notion of reference at the portal into the Go universe. You have types and pointer-types, and these types hold values.</p> <p>Hopefully this playground is a effective visual aid: <a href="https://play.golang.org/p/kEYFzTwbwR" rel="nofollow">https://play.golang.org/p/kEYFzTwbwR</a></p> <p>it prints a textual representation of the data, the textual representation closely resembles how this data is stored within memory.</p></pre>tjholowaychuk: <pre><p>In that scenario it&#39;s effectively the same as doing:</p> <pre><code>a := Vertex{} a.X = 5 </code></pre> <p>You&#39;re not getting a copy each time you assign the field, you&#39;re just moving the value 5 to X, whereas this will produce a copy first:</p> <pre><code>a := vertices[0] a.X = 5 vertices[0].X // won&#39;t be 5 :D </code></pre> <p>Same goes for the assignment in <code>for</code> though, this won&#39;t give you v.X == 5&#39;s</p> <pre><code>package main import &#34;fmt&#34; type Vertex struct { X int Y int } func main() { vs := []Vertex{ {1, 1}, {1, 1}, } for _, v := range vs { v.X = 5 } fmt.Printf(&#34;%#v\n&#34;, vs) } </code></pre></pre>binaryblade: <pre><p>maybe this will show the <a href="https://play.golang.org/p/XJC266-4LC" rel="nofollow">difference</a></p></pre>ardanstudios: <pre><p>Read this series. </p> <p><a href="https://www.goinggo.net/2017/05/language-mechanics-on-stacks-and-pointers.html" rel="nofollow">https://www.goinggo.net/2017/05/language-mechanics-on-stacks-and-pointers.html</a></p></pre>