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  1. using System;
  2. using System.Collections.Generic;
  3. using System.Linq;
  4.  
  5. public static class SimpleEnumerable
  6. {
  7.     public static IEnumerable<TSource> SimpleWhere<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate)
  8.     {
  9.     	foreach (TSource element in source)
  10.     	{
  11.     		if (predicate(element))
  12.     		{
  13.     			yield return element;
  14.     		}
  15.     	}
  16.     }
  17. }
  18.  
  19. public class MyClass
  20. {
  21.     private string _att01;
  22.     private string _att02;
  23.     private string _att03;
  24.     public int instanceNum;
  25.  
  26.     public string att01
  27.     {
  28.         get
  29.         {
  30.             Console.WriteLine("att01 of instance {0}", instanceNum);
  31.             return _att01;
  32.         }
  33.         set
  34.         {
  35.             _att01 = value;
  36.         }
  37.     }
  38.  
  39.     public string att02
  40.     {
  41.         get
  42.         {
  43.             Console.WriteLine("att02 of instance {0}", instanceNum);
  44.             return _att02;
  45.         }
  46.         set
  47.         {
  48.             _att02 = value;
  49.         }
  50.     }
  51.  
  52.     public string att03
  53.     {
  54.         get
  55.         {
  56.             Console.WriteLine("att03 of instance {0}", instanceNum);
  57.             return _att03;
  58.         }
  59.         set
  60.         {
  61.             _att03 = value;
  62.         }
  63.     }
  64. }
  65.  
  66. public class Test
  67. {
  68. 	public static void Main()
  69. 	{
  70. 	    var coll = new[] 
  71. 	    {
  72. 	        new MyClass { instanceNum = 0, att01 = "A", att02 = "B", att03 = "C" },
  73. 	        new MyClass { instanceNum = 1, att01 = "X", att02 = "B", att03 = "C" },
  74. 	        new MyClass { instanceNum = 2, att01 = "X", att02 = "Y", att03 = "C" },
  75. 	        new MyClass { instanceNum = 3, att01 = "X", att02 = "Y", att03 = "Z" },
  76. 	    };
  77.  
  78. 	    Console.WriteLine("Method 1");
  79. 	    var list1 = coll
  80. 	        .Where(x => x.att01 == "X")
  81. 	        .Where(x => x.att02 == "Y")
  82. 	        .Where(x => x.att03 == "Z")
  83. 	        .SingleOrDefault();
  84.  
  85. 	    Console.WriteLine();
  86. 	    Console.WriteLine("Method 2");
  87. 	    var list2 = coll
  88. 	        .Where(x => x.att01 == "X" && x.att02 == "Y" && x.att03 == "Z")
  89. 	        .SingleOrDefault();
  90.  
  91. 	    Console.WriteLine("Method 3");
  92. 	    var list3 = coll
  93. 	        .SimpleWhere(x => x.att01 == "X")
  94. 	        .SimpleWhere(x => x.att02 == "Y")
  95. 	        .SimpleWhere(x => x.att03 == "Z")
  96. 	        .SingleOrDefault();
  97.  
  98. 	}
  99. }
Success #stdin #stdout 0.04s 24264KB
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stdin
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Standard input is empty
stdout
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Method 1
att01 of instance 0
att01 of instance 1
att02 of instance 1
att01 of instance 2
att02 of instance 2
att03 of instance 2
att01 of instance 3
att02 of instance 3
att03 of instance 3

Method 2
att01 of instance 0
att01 of instance 1
att02 of instance 1
att01 of instance 2
att02 of instance 2
att03 of instance 2
att01 of instance 3
att02 of instance 3
att03 of instance 3
Method 3
att01 of instance 0
att01 of instance 1
att02 of instance 1
att01 of instance 2
att02 of instance 2
att03 of instance 2
att01 of instance 3
att02 of instance 3
att03 of instance 3
https://ideone.com/QAQZ65
language:
C# (gmcs 5.20.1)
created:
10 years ago
visibility:
public

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