string 如何获取 Golang 字符串的最后 X 个字符？
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How to get the last X Characters of a Golang String?
提问by sourcey
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 stringpackage and didn't see anything like getLastXcharacters.
如果我有字符串“12121211122”并且我想获取最后 3 个字符（例如“122”），这在 Go 中可行吗？我查看了string包裹，没有看到类似getLastXcharacters.
回答by OneOfOne
You can use a slice expressionon a string to get the last three bytes.
您可以在字符串上使用切片表达式来获取最后三个字节。
s := "12121211122"
first3 := s[0:3]
last3 := s[len(s)-3:]
Or if you're using unicode you can do something like:
或者，如果您使用的是 unicode，则可以执行以下操作：
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 Goand Slice Tricks.
回答by Simon Fox
The answer depends on what you mean by "characters". If you mean bytes then:
答案取决于您所说的“字符”是什么意思。如果你的意思是字节，那么：
s := "12121211122"
lastByByte := s[len(s)-3:]
If you mean runes in a utf-8 encoded string, then:
如果您的意思是 utf-8 编码字符串中的符文，则：
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.
您还可以将字符串转换为 []rune 并在 rune 切片上进行操作，但这会分配内存。
