什麼是Oracle IN語句的C＃等價物？

Question

我將如何檢查變量是否是幾個值之一？

凡IN在甲骨文會讀到這樣

where strVar in ('A','H','X','Z') 

，而無需編寫

if (strVar == "A" || strVar == "H" || strVar == "X" || strVar =="Z") 

---

editted改變變量名

Answer 1

這應該是夠你：

if(new string[]{"A","B",".."}.Contains(strVar)) { 
    .... CONTAINS ... 
} 

也還可以使用上C# 2.0

if(new string[]{"A","B",".."}.Any(strVar)) { 
    .... CONTAINS ... 
} 

但Contains的作品，而不是Any沒有。

編輯

由於正確地指出@brendan，擺脫var命名變量，即C#關鍵字，讓我們避免產生混淆。

Answer 2

沒有任何背景：

new [] {'A','H','X','Z'}.Contains(var);

Answer 3

這也許應該是你最好的選擇：

if ("hxza".Contains(value)) 

我做薩姆 「測試速度」 一些diferents方法可以做到你whant什麼去做。

您可以看到底部爲的代碼。需要注意的是X爲I重複測試，使平均

結果爲X = 1的時間數：

Average of ticks for test7 : 4 
Average of ticks for test2 : 5 
Average of ticks for test10 : 6 
Average of ticks for test9 : 7 
Average of ticks for test4 : 19 
Average of ticks for test8 : 35 
Average of ticks for test6 : 451 
Average of ticks for test5 : 2711 
Average of ticks for test1 : 3146 
Average of ticks for test3 : 8569 

結果爲X = 100：

Average of ticks for test2 : 3 
Average of ticks for test7 : 3 
Average of ticks for test10 : 3 
Average of ticks for test9 : 5 
Average of ticks for test4 : 5 
Average of ticks for test8 : 5 
Average of ticks for test6 : 11 
Average of ticks for test3 : 20 
Average of ticks for test5 : 23 
Average of ticks for test1 : 35 

結果對於X = 100 000：

Average of ticks for test2 : 3 
Average of ticks for test7 : 3 
Average of ticks for test5 : 3 
Average of ticks for test1 : 3 
Average of ticks for test6 : 3 
Average of ticks for test10 : 3 
Average of ticks for test9 : 5 
Average of ticks for test4 : 5 
Average of ticks for test8 : 5 
Average of ticks for test3 : 5 

所以我們可以告訴測試2,7和10是讓你想要什麼好辦法：

//test2 
if (value == 'a' || value == 'h' || value == 'x' || value == 'z') 

//test7 
if (value == 'h' || value == 'x' || value == 'z' || value == 'a') 

//test10 
if ("hxza".Contains(value)) 

看到代碼：

  char value = 'a'; 
      Dictionary<string, long> tests = new Dictionary<string, long>() 
      { 
       {"test1", 0}, 
       {"test2", 0}, 
       {"test3", 0}, 
       {"test4", 0}, 
       {"test5", 0}, 
       {"test6", 0}, 
       {"test7", 0}, 
       {"test8", 0}, 
       {"test9", 0}, 
       {"test10", 0} 
      }; 
      Stopwatch watch = new Stopwatch(); 
      // tested with 1, 100 and 100 000 
      long X = 1; 

      for (int i = 0; i < X; i++) 
      { 
       watch.Start(); 
       if ("ahxz".Any(c => c == value)) 
       { 
       } 
       watch.Stop(); 
       tests["test1"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if (value == 'a' || value == 'h' || value == 'x' || value == 'z') 
       { 
       } 
       watch.Stop(); 
       tests["test2"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if (new[] { 'a', 'h', 'x', 'z' }.Contains(value)) 
       { 
       } 
       watch.Stop(); 
       tests["test3"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if (new[] { 'a', 'h', 'x', 'z' }.Contains(value)) 
       { 
       } 
       watch.Stop(); 
       tests["test4"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if ("ahxz".Contains(value)) 
       { 
       } 
       watch.Stop(); 
       tests["test5"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if ("hxza".Any(c => c == value)) 
       { 
       } 
       watch.Stop(); 
       tests["test6"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if (value == 'h' || value == 'x' || value == 'z' || value == 'a') 
       { 
       } 
       watch.Stop(); 
       tests["test7"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if (new[] { 'h', 'x', 'z', 'a' }.Contains(value)) 
       { 
       } 
       watch.Stop(); 
       tests["test8"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if (new[] { 'h', 'x', 'z', 'a' }.Contains(value)) 
       { 
       } 
       watch.Stop(); 
       tests["test9"] += watch.ElapsedTicks; 
       watch.Reset(); 

       watch.Start(); 
       if ("hxza".Contains(value)) 
       { 
       } 
       watch.Stop(); 
       tests["test10"] += watch.ElapsedTicks; 
       watch.Reset(); 
      } 

      foreach (var test in tests.OrderBy(p => p.Value)) 
      { 
       Console.WriteLine("Average of ticks for {0} : {1}\n", test.Key, test.Value/nbrOfTimes); 
      } 

      Console.ReadLine();