因为你在阅读到答案评论询问是否是快/慢或只是更少的代码。我尝试了一下,并写了一个小的汽车类:
private static Random random = new Random((int)DateTime.Now.Ticks);
private static string RandomString(int min, int max)
{
string str = "";
int size = random.Next(min, max + 1);
for (int i = 0; i < size; i++)
str += Convert.ToChar(Convert.ToInt32(
Math.Floor(26 * random.NextDouble() + 65)));
return str;
}
public static void MeassureTicks(int numberCars, int minLength, int maxLength)
{
// Generate random list
List<Car> cars = Enumerable.Range(0, numberCars)
.Select(x => new Car(RandomString(
minLength, maxLength))).ToList();
Stopwatch sw1 = new Stopwatch(), sw2 = new Stopwatch(),
sw3 = new Stopwatch(), sw4 = new Stopwatch();
sw1.Start();
string concat1 = CreateConcatenatedList(cars);
sw1.Stop();
sw2.Start();
string concat2 = String.Join(",", cars.Select(c => c.Name).ToArray());
sw2.Stop();
sw3.Start();
if (numberCars <= 5000)
{
string concat3 = cars.Select(c => c.Name).Aggregate("",
(str, current) =>
{
return str.Length == 0 ? str = current :
str += "," + current;
}).ToString();
}
sw3.Stop();
sw4.Start();
string concat4 = cars.Select(c => c.Name).Aggregate(
new StringBuilder(), (sb, current) =>
{
return sb.Length == 0 ? sb.Append(current) :
sb.AppendFormat(",{0}", current);
}).ToString();
sw4.Stop();
Console.WriteLine(string.Format("{0} car strings joined:\n" +
"\tYour method: {1} ticks\n" +
"\tLinq+String.Join: {2} ticks\n" +
"\tLinq+Aggregate+String.Concat: {3} ticks\n" +
"\tLinq+Aggregate+StringBuilder: {4} ticks\n",
cars.Count, sw1.ElapsedTicks, sw2.ElapsedTicks,
numberCars <= 5000 ? sw3.ElapsedTicks.ToString() : "-",
sw4.ElapsedTicks));
更新:
public class Car
{
public string Name { get; set; }
public Car(string name) { Name = name; }
}
长度为5-10的随机生成的字符串测试它 我现在想这两种方法是也在使用聚合。
输出是在我的电脑的一些不同的汽车数量:
5 car strings joined:
Your method: 14 ticks
Linq+String.Join: 20 ticks
Linq+Aggregate+String.Concat: 11 ticks
Linq+Aggregate+StringBuilder: 15 ticks
50 car strings joined:
Your method: 50 ticks
Linq+String.Join: 45 ticks
Linq+Aggregate+String.Concat: 70 ticks
Linq+Aggregate+StringBuilder: 73 ticks
500 car strings joined:
Your method: 355 ticks
Linq+String.Join: 348 ticks
Linq+Aggregate+String.Concat: 5365 ticks
Linq+Aggregate+StringBuilder: 619 ticks
5000 car strings joined:
Your method: 3584 ticks
Linq+String.Join: 3357 ticks
Linq+Aggregate+String.Concat: 379635 ticks
Linq+Aggregate+StringBuilder: 6078 ticks
50000 car strings joined:
Your method: 33705 ticks
Linq+String.Join: 34082 ticks
Linq+Aggregate+String.Concat: - ticks
Linq+Aggregate+StringBuilder: 92839 ticks
500000 car strings joined:
Your method: 508439 ticks
Linq+String.Join: 376339 ticks
Linq+Aggregate+String.Concat: - ticks
Linq+Aggregate+StringBuilder: 616048 ticks
LINQ的+ String.Join
方法确实有点快和更少的代码。与StringBuilter
一起缩放非常好(不像字符串连接),但速度稍慢。因此,要么使用你的方法,要么Linq + String.Join
,这是一个很好的线上,也容易阅读。
对于大约一百万个解决方案,其中很多都是错误的,对于相关问题,请参阅http://blogs.msdn.com/ericlippert/archive/2009/04/15/comma-quibbling.aspx – 2010-05-12 14:07:12