package main

import (
	"fmt"
	"strings"
	"time"
)

func main() {
	const loopCount = 100000 // 10万次拼接
	var builder strings.Builder

	// 预分配内存（预估每个item占10字节，避免动态扩容）
	builder.Grow(loopCount * 10)

	start := time.Now()
	for i := 0; i < loopCount; i++ {
		fmt.Fprintf(&builder, "item_%d,", i) // 直接写入缓冲区，无临时字符串
	}
	result := builder.String()
	fmt.Printf("strings.Builder拼接耗时：%v\n", time.Since(start))
	_ = result // 避免未使用变量警告
}