C# |检查数组是否包含符合指定条件的元素

原文:https://www . geeksforgeeks . org/c-sharp-check-if-array-contain-the-elements-match-the-specific-conditions/

阵列。Exists(T[]，谓词< T >)方法用于检查指定数组是否包含与指定谓词定义的条件相匹配的元素。

语法:

public static bool Exists<T> (T[] array, Predicate<T> match);

参数:

数组:是一维的，从零开始搜索的数组。匹配:它是一个谓词，定义了要搜索的元素的条件。其中 T 是数组中元素的类型。

返回值:该方法的返回类型为系统。布尔。如果数组包含一个或多个与指定谓词定义的条件相匹配的元素，则返回 true 。否则，返回假。

异常:如果数组的值为空，或者匹配的值为空，该方法将给出 ArgumentNullException 。

下面给出了一些例子，以便更好地理解实现:

例 1:

// C# program to illustrate the 
// Array.Exists(T[], Predicate<T>) Method
using System;

class GFG {

    // Main method
    static public void Main()
    {

        // Create and initialize array
        string[] language = {"Ruby", "C", "C++", "Java",
                             "Perl", "C#", "Python", "PHP"};

        // Display language array
        Console.WriteLine("Display the array:");
        foreach(string i in language)
        {
            Console.WriteLine(i);
        }

        // Display and check the given elements
        // present in the array or not

        // Using Exists() method
        Console.WriteLine("Is Ruby part of language: {0}",
                          Array.Exists(language, element => element == "Ruby"));

        Console.WriteLine("Is VB part of language: {0}",
                          Array.Exists(language, element => element == "VB"));
    }
}

Output:

Display the array:
Ruby
C
C++
Java
Perl
C#
Python
PHP
Is Ruby part of language: True
Is VB part of language: False

例 2:

// C# program to illustrate the 
// Array.Exists(T[], Predicate<T>) Method
using System;

public class GFG {

// Main method
static public void Main()
{

    // Create and initialize array
    string[] ds = {"Array", "Queue", "LinkedList",
                               "Stack", "Graph" };

    // Display ds array
    Console.WriteLine("Given Array: ");

    foreach(string i in ds)
    {
        Console.WriteLine(i);
    }

    // Display and check the given elements with the
    // specified letter is present in the array or not
    // Using Exists() method
    Console.WriteLine("Is element start with L letter is present in array: {0}",
                      Array.Exists(ds, element => element.StartsWith("L")));

    Console.WriteLine("Is element start with O letter is present in array: {0}",
                      Array.Exists(ds, element => element.StartsWith("O")));
}
}

Output:

Given Array: 
Array
Queue
LinkedList
Stack
Graph
Is element start with L letter is present in array: True
Is element start with O letter is present in array: False

注:此法为 O(n)运算，其中 n 为数组长度。

参考:https://docs . Microsoft . com/en-us/dotnet/API/system . array . exists？视图= netcore-2.1 # 定义

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