package main

import (
	"os"
	"strings"
	"testing"
)

func echoAll1() string {
	var s, sep string
	for i := 0; i < len(os.Args); i++ {
		s += sep + os.Args[i]
		sep = " "
	}
	return s
}

func echoAll2() string {
	s, sep := "", ""
	for _, arg := range os.Args[:] {
		s += sep + arg
		sep = " | "
	}
	return s
}

func echoAll3() string {
	return strings.Join(os.Args[:], " , ")
}

// strings.Builder 是 Go 推薦的高效字符串拼接方式，尤其在循環(huán)中拼接時(shí)，
// 可以減少內(nèi)存分配。


func echoAll4() string {
	var builder strings.Builder
	for i, arg := range os.Args[:] {
		if i > 0 {
			builder.WriteString(" <> ")
		}
		builder.WriteString(arg)
	}
	return builder.String()
}


// ===== Benchmark Functions =====

func BenchmarkEchoAll1(b *testing.B) {
	// 模擬更長(zhǎng)參數(shù)列表，避免誤差過(guò)大
	originalArgs := os.Args
	os.Args = make([]string, 100)
	for i := range os.Args {
		os.Args[i] = "arg"
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = echoAll1()
	}
	os.Args = originalArgs // 恢復(fù)
}

func BenchmarkEchoAll2(b *testing.B) {
	originalArgs := os.Args
	os.Args = make([]string, 100)
	for i := range os.Args {
		os.Args[i] = "arg"
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = echoAll2()
	}
	os.Args = originalArgs
}

func BenchmarkEchoAll3(b *testing.B) {
	originalArgs := os.Args
	os.Args = make([]string, 100)
	for i := range os.Args {
		os.Args[i] = "arg"
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = echoAll3()
	}
	os.Args = originalArgs
}

func BenchmarkEchoAll4(b *testing.B) {
	originalArgs := os.Args
	os.Args = make([]string, 100)
	for i := range os.Args {
		os.Args[i] = "arg"
	}

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = echoAll4()
	}
	os.Args = originalArgs
}

go test -bench=. -benchmem