c# – 为什么StringBuilder比字符串连接慢?
发布时间:2020-12-15 03:43:45 所属栏目:百科 来源:网络整理
导读:为什么StringBuilder与连接相比较慢? StringBuilder旨在避免额外的对象创建,但是为什么会影响性能? static void Main(string[] args) { int max = 1000000; for (int times = 0; times 5; times++) { Console.WriteLine("ntime: {0}",(times+1).ToString(
为什么StringBuilder与连接相比较慢?
StringBuilder旨在避免额外的对象创建,但是为什么会影响性能? static void Main(string[] args) { int max = 1000000; for (int times = 0; times < 5; times++) { Console.WriteLine("ntime: {0}",(times+1).ToString()); Stopwatch sw = Stopwatch.StartNew(); for (int i = 0; i < max; i++) { string msg = "Your total is "; msg += "$500 "; msg += DateTime.Now; } sw.Stop(); Console.WriteLine("String +t: {0}ms",((int)sw.ElapsedMilliseconds).ToString().PadLeft(6)); sw = Stopwatch.StartNew(); for (int j = 0; j < max; j++) { StringBuilder msg = new StringBuilder(); msg.Append("Your total is "); msg.Append("$500 "); msg.Append(DateTime.Now); } sw.Stop(); Console.WriteLine("StringBuildert: {0}ms",((int)sw.ElapsedMilliseconds).ToString().PadLeft(6)); } Console.Read(); } 编辑:根据建议移出范围变量: 解决方法
更改,以使StringBuilder不被实例化,而不是.Clear()它:
time: 1 String + : 3348ms StringBuilder : 3151ms time: 2 String + : 3346ms StringBuilder : 3050ms 等等 请注意,这仍然测试完全相同的功能,但尝试重新使用资源一点更聪明. 代码:(也住在http://ideone.com/YuaqY) using System; using System.Text; using System.Diagnostics; public class Program { static void Main(string[] args) { int max = 1000000; for (int times = 0; times < 5; times++) { { Console.WriteLine("ntime: {0}",(times+1).ToString()); Stopwatch sw = Stopwatch.StartNew(); for (int i = 0; i < max; i++) { string msg = "Your total is "; msg += "$500 "; msg += DateTime.Now; } sw.Stop(); Console.WriteLine("String +t: {0}ms",((int)sw.ElapsedMilliseconds).ToString().PadLeft(6)); } { Stopwatch sw = Stopwatch.StartNew(); StringBuilder msg = new StringBuilder(); for (int j = 0; j < max; j++) { msg.Clear(); msg.Append("Your total is "); msg.Append("$500 "); msg.Append(DateTime.Now); } sw.Stop(); Console.WriteLine("StringBuildert: {0}ms",((int)sw.ElapsedMilliseconds).ToString().PadLeft(6)); } } Console.Read(); } } (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |