在go lang字节包中找不到NewBuffer（[] bytes，int，int64）方法

Question

I'm new in go language. I'm trying to understand what's happening inside ioutil.ReadAll(r Reader, capacity int64) method. Inside this method there is a line like:

buf := bytes.NewBuffer(make([]byte, 0, capacity))

But the problem is inside bytes package there is a NewBuffer method with only parameter like:

func NewBuffer(buf []byte) *Buffer

I searched bytes package documentation again and again but can't find NewBuffer method with 3 parameter.

So actually from where NewBuffer(make([]byte, int, int64)) method calling?

Answer 1

make([]byte, 0, capacity) returns a new byte slice ([]byte) initialized to length 0 and capacity capacity.

In other words, it might help you to see it on multiple lines:

capacity := 100 // or whatever
var myBytes []byte = make([]byte, 0, capacity)
buf := bytes.NewBuffer(myBytes)