爲什麼不能在string
上使用流利的語言?將IEnumerable <char>轉換爲字符串的最佳方法?
例如:
var x = "asdf1234";
var y = new string(x.TakeWhile(char.IsLetter).ToArray());
是不是有更好的辦法來IEnumerable<char>
轉換爲string
?
這裏是我做了一個試驗:
class Program
{
static string input = "asdf1234";
static void Main()
{
Console.WriteLine("1000 times:");
RunTest(1000, input);
Console.WriteLine("10000 times:");
RunTest(10000,input);
Console.WriteLine("100000 times:");
RunTest(100000, input);
Console.WriteLine("100000 times:");
RunTest(100000, "ffff57467");
Console.ReadKey();
}
static void RunTest(int times, string input)
{
Stopwatch sw = new Stopwatch();
sw.Start();
for (int i = 0; i < times; i++)
{
string output = new string(input.TakeWhile(char.IsLetter).ToArray());
}
sw.Stop();
var first = sw.ElapsedTicks;
sw.Restart();
for (int i = 0; i < times; i++)
{
string output = Regex.Match(input, @"^[A-Z]+",
RegexOptions.IgnoreCase).Value;
}
sw.Stop();
var second = sw.ElapsedTicks;
var regex = new Regex(@"^[A-Z]+",
RegexOptions.IgnoreCase);
sw.Restart();
for (int i = 0; i < times; i++)
{
var output = regex.Match(input).Value;
}
sw.Stop();
var third = sw.ElapsedTicks;
double percent = (first + second + third)/100;
double p1 = (first/percent)/ 100;
double p2 = (second/percent)/100;
double p3 = (third/percent )/100;
Console.WriteLine("TakeWhile took {0} ({1:P2}).,", first, p1);
Console.WriteLine("Regex took {0}, ({1:P2})." , second,p2);
Console.WriteLine("Preinstantiated Regex took {0}, ({1:P2}).", third,p3);
Console.WriteLine();
}
}
結果:
1000 times:
TakeWhile took 11217 (62.32%).,
Regex took 5044, (28.02%).
Preinstantiated Regex took 1741, (9.67%).
10000 times:
TakeWhile took 9210 (14.78%).,
Regex took 32461, (52.10%).
Preinstantiated Regex took 20669, (33.18%).
100000 times:
TakeWhile took 74945 (13.10%).,
Regex took 324520, (56.70%).
Preinstantiated Regex took 172913, (30.21%).
100000 times:
TakeWhile took 74511 (13.77%).,
Regex took 297760, (55.03%).
Preinstantiated Regex took 168911, (31.22%).
結論:我懷疑什麼是最好的話,我想我會在TakeWhile
去這是第一次運行時最慢的。
無論如何,我的問題是,是否有任何方法通過restringing TakeWhile
函數的結果來優化性能。
請解釋一下你的意思是「最好」:最快?最少的記憶飢餓?最容易理解? – LukeH
@LukeH我已經決定要選擇什麼:緊固件。我的問題是,如果有比'新字符串(x.TakeWhile(p).ToArray)更好的方法'' – Shimmy
@LukeH:可能想要取消刪除您的解決方案:它比我的速度快很多 – BrokenGlass