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迭代KeyValuePair(作为字典中的键)不起作用

ienumerable dictionary unit-testing c#

OldSchool · 技术社区 · 8 年前

public void deleteAllCarsWithType(Dictionary < KeyValuePair<string, string> , car > dictCar, string typeOfCar)
{
  var keyValuePairs = dictCar.Where(keyValuePair => keyValuePair.Key.Equals(typeOfCar));

  //var count = keyValuePairs.Count();
  //this also gives the size of keyValuePairs as 0.

  foreach (var keyValuePair in keyValuePairs)
  {
    dictCar.Remove(keyValuePair.Key);
  }
}

KeyValuePair<string, string> 哪一个是字典的关键,有 carType carModel 作为汽车的模型。

当我运行它的单元测试时

[TestMethod]
public void DeleteSameCarTypeTest()
{
  Dictionary<KeyValuePair<string, string>, car> Dictionary = new Dictionary<KeyValuePair<string, string>, car>();
  Dictionary.Add(new KeyValuePair<string, string>("x", "y"), new car());
  Dictionary.Add(new KeyValuePair<string, string>("x", "z"), new car());

  new Program().deleteAllCarsWithType(Dictionary, "x");
  Assert.AreEqual(0, Dictionary.Count);
}

它失败了,说预期 0 2 .

当我调试它时,我发现 keyValuePairs 具有预期的两个值(与 车辆类型 键值对 是 0 Count 的也即将到来 . 我不知道我做错了什么。请帮帮我。

2 回复 | 直到 8 年前

Yair Halberstadt 8 年前

您需要:

var keyValuePairs = dictCar.Where(keyValuePair => keyValuePair.Key.Key.Equals(typeOfCar));

private static void deleteAllCarsWithType(Dictionary<KeyValuePair<string, string>, car> dictCar, string typeOfCar)
{
    var keyValuePairs = dictCar.Where(keyValuePair => keyValuePair.Key.Key.Equals(typeOfCar)).ToArray();

    foreach (var keyValuePair in keyValuePairs)
    {
        dictCar.Remove(keyValuePair.Key);
    }               
}

JuanR 8 年前

您正在查看与键相反的值。

将代码更改为:

private static void deleteAllCarsWithType(Dictionary<KeyValuePair<string, string>, car> dictCar, string typeOfCar)
{
    var keyValuePairs = dictCar.Keys.Where(keyValuePair => keyValuePair.Key.Equals(typeOfCar)).ToArray();

    foreach (var keyValuePair in keyValuePairs)
    {
        dictCar.Remove(keyValuePair);
    }               
}

注意,我还将查询转换为数组。否则,由于修改了集合,循环将失败。

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