C# |移除列表中所有与谓词
定义的条件相匹配的元素
原文:https://www . geeksforgeeks . org/c-sharp-移除符合谓词定义的条件的列表中的所有元素/
列表< T >。RemoveAll(谓词< T >)方法用于移除所有与指定谓词定义的条件相匹配的元素。
列表属性:
- 它不同于数组。列表可以动态调整大小，但数组不能。
- 列表类可以接受 null 作为引用类型的有效值，并且它还允许重复的元素。
- 如果计数等于容量，则通过重新分配内部阵列，列表的容量会自动增加。在添加新元素之前，现有元素将被复制到新数组中。
语法:
public int RemoveAll (Predicate<T> match);
参数:
匹配:是谓词< T >委托定义了要移除的元素的条件。
返回值:该方法返回要从列表<中删除的元素数量>。
异常:如果匹配为空，此方法将给出 ArgumentNullException 。
以下程序说明了列表< T >的使用。移除所有(谓词< T >)方法:
例 1:
// C# Program to remove all elements of
// a List that match the conditions
// defined by the predicate
using System;
using System.Collections;
using System.Collections.Generic;
class Geeks {
// function which checks whether an
// element is even or not. Or you can
// say it is the specified condition
private static bool isEven(int i)
{
return ((i % 2) == 0);
}
// Main Method
public static void Main(String[] args)
{
// Creating an List<T> of Integers
List<int> firstlist = new List<int>();
// Adding elements to List
for (int i = 1; i <= 10; i++) {
firstlist.Add(i);
}
Console.WriteLine("Elements Present in List:\n");
// Displaying the elements of List
foreach (int k in firstlist)
{
Console.WriteLine(k);
}
Console.WriteLine(" ");
Console.Write("Number of Elements Removed: ");
// Removing the elements which is even
// This will return 5 as it removed 5
// even elements from the list
Console.WriteLine(firstlist.RemoveAll(isEven));
Console.WriteLine(" ");
Console.WriteLine("Remaining Elements in List:");
// Displaying the elements of List
foreach (int k in firstlist)
{
Console.WriteLine(k);
}
}
}
输出:
Elements Present in List:
1
2
3
4
5
6
7
8
9
10
Number of Elements Removed: 5
Remaining Elements in List:
1
3
5
7
9
例 2:
// C# Program to remove all elements of
// a List that match the conditions
// defined by the predicate
using System;
using System.Collections;
using System.Collections.Generic;
class Geeks {
// function which checks whether an
// element is even or not. Or you can
// say it is the specified condition
private static bool isEven(int i)
{
return ((i % 2) == 0);
}
// Main Method
public static void Main(String[] args)
{
// Creating an List<T> of Integers
List<int> firstlist = new List<int>();
// Adding items to List
firstlist.Add(13);
firstlist.Add(17);
firstlist.Add(19);
firstlist.Add(11);
Console.WriteLine("Elements Present in List:\n");
// Displaying the elements of List
foreach(int k in firstlist)
{
Console.WriteLine(k);
}
Console.WriteLine(" ");
Console.Write("Number of Elements Removed: ");
// Removing the elements which is even
// This will return 0 as it no elements
// are even in List
Console.WriteLine(firstlist.RemoveAll(isEven));
Console.WriteLine(" ");
Console.WriteLine("Remaining Elements in List:");
// Displaying the elements of List
foreach (int k in firstlist)
{
Console.WriteLine(k);
}
}
}
输出:
Elements Present in List:
13
17
19
11
Number of Elements Removed: 0
Remaining Elements in List:
13
17
19
11
参考:
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