如何有效地连接 Go 中的字符串？

Question

In Go, a string is a primitive type, which means it is read-only, and every manipulation of it will create a new string.

So if I want to concatenate strings many times without knowing the length of the resulting string, what's the best way to do it?

The naive way would be:

s := ""
for i := 0; i < 1000; i++ {
    s += getShortStringFromSomewhere()
}
return s

but that does not seem very efficient.

转载于:https://stackoverflow.com/questions/1760757/how-to-efficiently-concatenate-strings-in-go

Answer 1

The best way is to use the bytes package. It has a Buffer type which implements io.Writer.

package main

import (
    "bytes"
    "fmt"
)

func main() {
    var buffer bytes.Buffer

    for i := 0; i < 1000; i++ {
        buffer.WriteString("a")
    }

    fmt.Println(buffer.String())
}

This does it in O(n) time.

Note added in 2018

From Go 1.10 there is the strings.Builder type, which achieves this even more efficiently (for strings). The example given there is succinct and easy to copy/adapt.

This is analogous to the StringBuilder class in Java.