为什么不能使用流利的语言string
?
例如:
var x = "asdf1234";
var y = new string(x.TakeWhile(char.IsLetter).ToArray());
难道没有更好的转换IEnumerable<char>
方式string
吗?
这是我做的一个测试:
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();
}
}
结果:
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%).
结论:我怀疑什么是更好的选择,我想我会继续,TakeWhile
只有在第一次运行时最慢。
无论如何,我的问题是是否有任何方法可以通过重新排列函数的结果来优化性能TakeWhile
。