C#返回在字典或列表中指定的序列中满足条件的元素数量 dictionary.count

例如字典重载的方法：Dictionary.Count方法

class Pet
{
public string Name { get; set; }
public bool Vaccinated { get; set; }
}

public static void CountEx2()
{
Pet[] pets = { new Pet { Name="Barley", Vaccinated=true },
new Pet { Name="Boots", Vaccinated=false },
new Pet { Name="Whiskers", Vaccinated=false } };

try
{
int numberUnvaccinated = pets.Count(p => p.Vaccinated == false);
Console.WriteLine("There are {0} unvaccinated animals.", numberUnvaccinated);
}
catch (OverflowException)
{
Console.WriteLine("The count is too large to store as an Int32.");
Console.WriteLine("Try using the LongCount() method instead.");
}
}