如何返回整数字节数组中的最后一个元素

Question

In Go, I want to find the last element in an array of integers.

I have a list:

    [0.0.1, 0.0.2, 0.0.3]

I just want:

    0.0.3

Every time I try to return the last element the console returns

    %!(EXTRA uint8=10)

Which I assume means I need to convert a byte array to a slice?

Here's my code:

cmd := exec.Command("git", "tag")
out, err := cmd.CombinedOutput()
if err != nil {
    log.Fatalf("cmd.Run() failed with %s
", err)
}
fmt.Printf("Variable Type:
%s
", reflect.TypeOf(out))
fmt.Printf("Variable:
%s
", (out))

slice := out[0: len(out)]
releaseVersion := slice[len(slice) - 1]
fmt.Printf("release version:", releaseVersion)

Here's the output:

Variable Type:
[]uint8

Variable:
0.0.1
0.0.2
0.0.3

release version:%!(EXTRA uint8=10)

Answer 1

The reason you see: %!(EXTRA uint8=10) is you are calling Printf without a format option. You should just call fmt.Println instead.

10 is the encoding of the newline character.

Now, the meat of your question:

You have a byte array (slice).

You are trying to interpret it as lines (strings separated by ' ').

Interpreting a byte array as a string is easy (assuming the bytes do in fact represent a utf-8 string):

// assume buf is []byte
var text = string(buf)

You want to treat this as a list of strings. Since git tag returns lines, you can split by ' ' or you can just call strings.Fields which splits by generic whitespace (including newlines); documented here: https://golang.org/pkg/strings/#Fields

var parts = strings.Fields(text)

Now you can easily just get the last element:

parts[len(parts)-1]

But for safety you should check the list has some elements, otherwise you will crash on out-of-bounds access.

cmd := exec.Command("git", "tag")
bufOut, err := cmd.Output()
if err != nil {
    log.Fatalf("cmd.Run() failed with %s
", err)
}
textOut := string(bufOut)
parts := strings.Fields(textOut)
if len(parts) == 0 {
    log.Fatal("No tags")
}
releaseVersion := parts[len(parts)-1]
fmt.Println("release version:", releaseVersion)

WHY DOES THIS GOT TO BE SO COMPLEX? IN JAVASCRIPT I CAN JUST DO pop()

It's not really that complex. This is just how computers work. When a program runs, it has a standard output which is essentially a byte stream.

I'm guessing javascript does this step for you automatically:

textOut := string(bufOut)
parts := strings.Fields(textOut)

i.e. converting the program output to a list of strings separated by new lines.