为什么TrimLeft不能按预期工作？

Question

I've expected tag to be "account" but it is "ccount". Why is "a" removed?

package main

import "fmt"
import "strings"

func main() {
    s := "refs/tags/account"
    tag := strings.TrimLeft(s, "refs/tags")
    fmt.Println(tag)
}

Run

Answer 1

It is working as documented :

TrimLeft returns a slice of the string s with all leading Unicode code points contained in cutset removed

Because there's an 'a' in the first argument (the cutset) the leading 'a' in account is removed

Answer 2

Use TrimPrefix instead of TrimLeft

package main

import "fmt"
import "strings"

func main() {
    s := "refs/tags/account"
    tag := strings.TrimPrefix(s, "refs/tags/")
    fmt.Println(tag)
}

Please notice that following TrimLeft calls will result the same "fghijk " string:

package main

import (
        "fmt"
        "strings"
)

func main() {
    s := "/abcde/fghijk"
    tag := strings.TrimLeft(s, "/abcde")
    fmt.Println(tag)    
    tag = strings.TrimLeft(s, "/edcba")
    fmt.Println(tag)
}

So TrimLeft is not the method which fits your needs. I guess it's impossible to use it in the example you've given to get the result you expect.