在 golang 中打印 arrays 最有效的方法是什么

Question

我是编程新手，想了解更多关于内置函数的信息：

这是程序：

func main() {
    start := time.Now()

    fmt.Println(os.Args)

    fmt.Println(time.Since(start))
}

及其 output：

[AB C DEFGHIJKLMNOP] 124.009µs

这是我的 for 循环：

package main

import (
"fmt"
"os"
"time"
)

func main() {
start := time.Now()

    var s string
    for i:=0; i<len(os.Args); i++{
        s += os.Args[i] + " " 
    }
    fmt.Println(s)
    
    fmt.Println(time.Since(start))

}

使用以下 output：

/tmp/go-build994847456/b001/exe/main AB C DEFGHIJKLMNOP 25.71µs

我期望标准库中内置的 function 会更快。

切片会使我的代码效率降低吗？

我应该使用 for 循环还是标准库fmt.println ？

我也很困惑strings.Join(os.Args\[1:\], " ")将如何执行 74.293µs

Answer 1

使用基准：

var slice = []string{"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P"}

func BenchmarkFMT(b *testing.B) {
    b.ReportAllocs()
    for n := 0; n < b.N; n++ {
        _ = fmt.Sprint(slice)
    }
}

func BenchmarkStringConcat(b *testing.B) {
    b.ReportAllocs()
    for n := 0; n < b.N; n++ {
        var str string
        for _, s := range slice {
            str += s + " "
        }
    }
}

func BenchmarkStringsBuilder(b *testing.B) {
    b.ReportAllocs()
    for n := 0; n < b.N; n++ {
        var l int
        for _, s := range slice {
            l += len(s)
        }
        var sb strings.Builder
        sb.Grow(l + len(slice)*len(" "))
        for _, s := range slice {
            sb.WriteString(s)
            sb.WriteString(" ")
        }
        _ = sb.String()
    }
}

func BenchmarkStringsJoin(b *testing.B) {
    b.ReportAllocs()
    for n := 0; n < b.N; n++ {
        _ = strings.Join(slice, " ")
    }
}

BenchmarkFMT
BenchmarkFMT-8                    734088          1633 ns/op         616 B/op         34 allocs/op
BenchmarkStringConcat
BenchmarkStringConcat-8          1290666           919.1 ns/op      1200 B/op         32 allocs/op
BenchmarkStringsBuilder
BenchmarkStringsBuilder-8        6074888           198.6 ns/op        64 B/op          1 allocs/op
BenchmarkStringsJoin
BenchmarkStringsJoin-8           4941542           241.7 ns/op        64 B/op          1 allocs/op
PASS