System.Comparison<T> 理解

System.Comparison<T> 定义如下:

public delegate int Comparison<in T>(T x, T y);

这意味着它是 delegate

此代码可以用lambda表达式重写如下:

collection.Sort((i1, i2) => i1.ToString().CompareTo(i2.ToString()));

下面的代码片段可以更好地解释发生了什么:

public static class TestClass {

  public static void Main(string[] args){
      Comparison<Int32> comparisonDelegate = CompareWithCase;
      //We now can use comparisonDelegate as though it is a method;
      int result = comparisonDelegate(1,2);
  }

  public static int CompareWithCase(int i1, int i2)
  {
     return i1.ToString().CompareTo(i2.ToString());
  } 
}

System.Comparison<T> 代表。

public delegate int Comparison<in T>(
    T x,
    T y
)

CompareWithCase 方法使它完全可分配给 Comparison<int> .

请注意,如果没有类型推断,您的 Sort

 collection.Sort(new Comparison<int>(MyComparer.CompareWithCase));

List<T>.Sort 期待 IComparer<T>