从 List<myType> 获取最大值
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Get Max value from List<myType>
提问by Waheed
I have List List<MyType>, my type contains Ageand RandomID
我有 List List<MyType>，我的类型包含Age和RandomID
Now I want to find the maximum age from this list.
现在我想从这个列表中找到最大年龄。
What is the simplest and most efficient way?
最简单有效的方法是什么？
采纳答案by Jon Skeet
Okay, so if you don't have LINQ, you could hard-code it:
好的，如果您没有 LINQ，则可以对其进行硬编码：
public int FindMaxAge(List<MyType> list)
{
if (list.Count == 0)
{
throw new InvalidOperationException("Empty list");
}
int maxAge = int.MinValue;
foreach (MyType type in list)
{
if (type.Age > maxAge)
{
maxAge = type.Age;
}
}
return maxAge;
}
Or you could write a more general version, reusable across lots of list types:
或者您可以编写一个更通用的版本，可在许多列表类型中重用：
public int FindMaxValue<T>(List<T> list, Converter<T, int> projection)
{
if (list.Count == 0)
{
throw new InvalidOperationException("Empty list");
}
int maxValue = int.MinValue;
foreach (T item in list)
{
int value = projection(item);
if (value > maxValue)
{
maxValue = value;
}
}
return maxValue;
}
You can use this with:
您可以将其用于：
// C# 2
int maxAge = FindMaxValue(list, delegate(MyType x) { return x.Age; });
// C# 3
int maxAge = FindMaxValue(list, x => x.Age);
Or you could use LINQBridge:)
或者你可以使用LINQBridge:)
In each case, you can return the if block with a simple call to Math.Maxif you want. For example:
在每种情况下，您都可以通过简单调用Math.Maxif来返回 if 块。例如：
foreach (T item in list)
{
maxValue = Math.Max(maxValue, projection(item));
}
回答by Kobi
Assuming you have access to LINQ, and Ageis an int(you may also try var maxAge- it is more likely to compile):
假设您可以访问 LINQ，并且Age是一个int（您也可以尝试var maxAge- 它更有可能编译）：
int maxAge = myTypes.Max(t => t.Age);
If you also need the RandomID(or the whole object), a quick solution is to use MaxByfrom MoreLinq
如果您还需要RandomID（或整个对象），一个快速的解决方案是使用MaxBy从MoreLinq
MyType oldest = myTypes.MaxBy(t => t.Age);
回答by anishMarokey
回答by thelost
thelist.Max(e => e.age);
回答by ch007
var maxAge = list.Max(x => x.Age);
回答by Jason Newland
Easiest way is to use System.Linq as previously described
最简单的方法是使用 System.Linq 如前所述
using System.Linq;
public int GetHighestValue(List<MyTypes> list)
{
return list.Count > 0 ? list.Max(t => t.Age) : 0; //could also return -1
}
This is also possible with a Dictionary
这也可以使用字典
using System.Linq;
public int GetHighestValue(Dictionary<MyTypes, OtherType> obj)
{
return obj.Count > 0 ? obj.Max(t => t.Key.Age) : 0; //could also return -1
}
回答by Behnam Rasooli
How about this way:
这种方式怎么样：
List<int> myList = new List<int>(){1, 2, 3, 4}; //or any other type
myList.Sort();
int greatestValue = myList[ myList.Count - 1 ];
You basically let the Sort()method to do the job for you instead of writing your own method. Unless you don't want to sort your collection.
您基本上让Sort()方法为您完成工作，而不是编写自己的方法。除非你不想整理你的收藏。
回答by Emile
Simplest is actually just Age.Max(), you don't need any more code.
最简单的其实只是Age.Max()，你不需要更多的代码。
