How to remove the last character of a string in Golang?

I want to remove the very last character of a string, but before I do so I want to check if the last character is a "+". How can this be done?

Here are several ways to remove trailing plus sign(s).

package main

import (
	"fmt"
	"strings"
)

func TrimSuffix(s, suffix string) string {
	if strings.HasSuffix(s, suffix) {
		s = s[:len(s)-len(suffix)]
	}
	return s
}

func main() {
	s := "a string ++"
	fmt.Println("s: ", s)

	// Trim one trailing '+'.
	s1 := s
	if last := len(s1) - 1; last >= 0 && s1[last] == '+' {
		s1 = s1[:last]
	}
	fmt.Println("s1:", s1)

	// Trim all trailing '+'.
	s2 := s
	s2 = strings.TrimRight(s2, "+")
	fmt.Println("s2:", s2)

	// Trim suffix "+".
	s3 := s
	s3 = TrimSuffix(s3, "+")
	fmt.Println("s3:", s3)
}

Output:

s:  a string ++
s1: a string +
s2: a string 
s3: a string +

Based on the comment of @KarthikGR the following example was added:

https://play.golang.org/p/ekDeT02ZXoq

package main

import (
	"fmt"
	"strings"
)

func main() {
	fmt.Println(strings.TrimSuffix("Foo++", "+"))
}

returns:

Foo+

No builtin way. But it's trivial to do manually.

s := "mystring+"
sz := len(s)

if sz > 0 && s[sz-1] == '+' {
    s = s[:sz-1]
}

@llazzaro

A simple UTF compliant string trimmer is

string([]rune(foo)[:len(foo)-1]))

So I'd go with

f2 := []rune(foo)
for f2[len(f2)-1] == '+'{
    f2 = f2[:len(f2)-1]
}
foo = string(f2)

https://go.dev/play/p/anOwXlfQWaF

I'm not sure why the other answers trimmed the way that they do, because they're trimming bytes.