CODEWITHSUNDEEP
stringgocharacter
sourcey
sourcey

Reputation: 2691

How to get the last X Characters of a Golang String?

If I have the string "12121211122" and I want to get the last 3 characters (e.g. "122"), is that possible in Go? I've looked in the string package and didn't see anything like getLastXcharacters.

Upvotes: 108

Views: 144938

Answers (2)

Simon Fox
Simon Fox

Reputation: 6425

The answer depends on what you mean by "characters". If you mean bytes then:

s := "12121211122"
lastByByte := s[len(s)-3:]

If you mean runes in a utf-8 encoded string, then:

s := "12121211122"
j := len(s)
for i := 0; i < 3 && j > 0; i++ {
    _, size := utf8.DecodeLastRuneInString(s[:j])
    j -= size
}
lastByRune := s[j:]

You can also convert the string to a []rune and operate on the rune slice, but that allocates memory.

Upvotes: 19

OneOfOne
OneOfOne

Reputation: 99244

You can use a slice expression on a string to get the last three bytes.

s      := "12121211122"
first3 := s[0:3]
last3  := s[len(s)-3:]

Or if you're using unicode you can do something like:

s      := []rune("世界世界世界")
first3 := string(s[0:3])
last3  := string(s[len(s)-3:])

Check Strings, bytes, runes and characters in Go and Slice Tricks.

Upvotes: 186

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