c# 排序列表<KeyValuePair<int, string>>
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c# Sorting a List<KeyValuePair<int, string>>
提问by CodeKingPlusPlus
In C# I would like to sort a List<KeyValuePair<int, string>>by the length of each string in the list. In Psuedo-Java this would be an anonymous and would look something like:
在 C# 中，我想List<KeyValuePair<int, string>>按列表中每个字符串的长度对 a 进行排序。在 Psuedo-Java 中，这将是一个匿名的，看起来像：
Collections.Sort(someList, new Comparator<KeyValuePair<int, string>>( {
public int compare(KeyValuePair<int, string> s1, KeyValuePair<int, string> s2)
{
return (s1.Value.Length > s2.Value.Length) ? 1 : 0; //specify my sorting criteria here
}
});
- How do I get the above functionality?
- 如何获得上述功能？
采纳答案by Guffa
The equivalent in C# would be to use a lambda expression and the Sortmethod:
C# 中的等价物是使用 lambda 表达式和Sort方法：
someList.Sort((x, y) => x.Value.Length.CompareTo(y.Value.Length));
You can also use the OrderByextension method. It's slightly less code, but it adds more overhead as it creates a copy of the list instead of sorting it in place:
您也可以使用OrderBy扩展方法。它的代码略少，但它增加了更多的开销，因为它创建了列表的副本而不是就地排序：
someList = someList.OrderBy(x => x.Value.Length).ToList();
回答by BrunoLM
You can use linq calling OrderBy
您可以使用 linq 调用OrderBy
list.OrderBy(o => o.Value.Length);
For more info on what @Guffa pointed out look for Linq and Deferred Execution, basically it will only execute when needed. So to immediately return a list from this line you need to add a .ToList()which will make the expression to be executed returning a list.
有关@Guffa 指出的更多信息，请查找Linq 和 Deferred Execution，基本上它只会在需要时执行。因此，要立即从这一行返回一个列表，您需要添加一个.ToList()，这将使要执行的表达式返回一个列表。
回答by Guffa
u can use this
你可以用这个
using System;
using System.Collections.Generic;
class Program
{
static int Compare1(KeyValuePair<string, int> a, KeyValuePair<string, int> b)
{
return a.Key.CompareTo(b.Key);
}
static int Compare2(KeyValuePair<string, int> a, KeyValuePair<string, int> b)
{
return a.Value.CompareTo(b.Value);
}
static void Main()
{
var list = new List<KeyValuePair<string, int>>();
list.Add(new KeyValuePair<string, int>("Perl", 7));
list.Add(new KeyValuePair<string, int>("Net", 9));
list.Add(new KeyValuePair<string, int>("Dot", 8));
// Use Compare1 as comparison delegate.
list.Sort(Compare1);
foreach (var pair in list)
{
Console.WriteLine(pair);
}
Console.WriteLine();
// Use Compare2 as comparison delegate.
list.Sort(Compare2);
foreach (var pair in list)
{
Console.WriteLine(pair);
}
}
}
