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Accepted
dgzargo
Asked:2020-10-02 23:19:54 +0000 UTC2020-10-02 23:19:54 +0000 UTC

如何转换为泛型类型？

  • 772
private bool TryParseOf<TType>(string s, out TType result)
{
    if (typeof(TType) == typeof(int))
    {
        var parseSuccessful = int.TryParse(s, out var innerResult);
        result = innerResult; // в этой строке проблема
        return parseSuccessful;
    }
    throw new NotImplementedException();
}

你不能只是把它拿走。TType也许int, string, 等等

c#

3 个回答

  1. Best Answer
    private bool TryParseOf<TType>(string s, out TType result)
{
    var converter = TypeDescriptor.GetConverter(typeof(TType));
    try
    {
        result = (TType)converter.ConvertFromString(s);
    }
    catch (ArgumentException)
    {
        result = default;
        return false;
    }
    return true;
}
    • 3

  2. 如果我们为简单类型做，那么

    public class MyClass
{
    public bool TryParseOf<TType>(string s, out TType result)
    {
        var converter = TypeDescriptor.GetConverter(typeof(TType));
        if (converter.CanConvertFrom(typeof(string)))
        {
            result = (TType)converter.ConvertFrom(s);
            return true;
        }
        result = default(TType);
        return false;
    }
}

    考试

    var c = new MyClass();  
if (c.TryParseOf("11", out int i)) Console.WriteLine(i); // 11
if (c.TryParseOf("11", out double j)) Console.WriteLine(j); // 11
    • 3

  3. 原则上，演员表可以通过 完成object，但我不确定届时是否会有额外的打包和拆包。如果他们这样做，那么我真的不喜欢这种方法。

    https://ideone.com/ziADyJ

    using System;

public class Test
{
  private static bool TryParseOf<TType>(string s, out TType result)
  {
    if (typeof(TType) == typeof(int))
    {
      var parseSuccessful = int.TryParse(s, out int innerResult);
      result = (TType)(object)innerResult;
      return parseSuccessful;
    }

    throw new NotImplementedException();
  }

  public static void Main()
  {
    Console.WriteLine("{0}: {1}", TryParseOf1<int>("123", out var x), x);
  }
}
    • 3

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