c#，检查整数数组中是否有负数

本文关键字：是否 数组 检查 整数 | 更新日期: 2023-09-27 18:10:12

我有一个数组int[] numArray。我想知道有没有直接的方法来检查数组中是否有负数?

如果没有直接的方法，即使linq也可以。我对linq有点陌生。谁能建议一下?

c#，检查整数数组中是否有负数

如果您愿意使用LINQ:

var containsNegatives = numArray.Any(n => n < 0);

或者，如果你想用"老式"的方式……你只需要循环:

var containsNegatives = false;
foreach(var n in numArray)
{
    if(n < 0)
    {
        containsNegatives = true;
        break;
    }
}

如果你真的想要更花哨，你可以把它变成一个扩展方法:

public static class EnumerableExtensions
{
    public static bool ContainsNegatives(this IEnumerable<int> numbers)
    {
        foreach(n in numbers)
        {
            if(n < 0) return true;
        }
        return false;
    }
}

并从代码中调用它，如:

var containsNegatives = numArray.ContainsNegatives();

你可以使用Any:

bool containsNegative = numArray.Any(i => i < 0)

或

bool containsNegative = numArray.Min() < 0;

编辑

int[] negativeNumbers = numArray.Where(i => i < 0).ToArray();

var negativeExist = numArray.Any(a => a < 0);

您可以使用Array.Find(T)方法执行此任务。

public static T Find<T>(
    T[] array,
    Predicate<T> match
)
例如,

using System;
using System.Drawing;
public class Example
{
    public static void Main()
    {
        // Create an array of five Point structures.
        Point[] points = { new Point(100, 200), 
            new Point(150, 250), new Point(250, 375), 
            new Point(275, 395), new Point(295, 450) };
        // To find the first Point structure for which X times Y 
        // is greater than 100000, pass the array and a delegate
        // that represents the ProductGT10 method to the static 
        // Find method of the Array class. 
        Point first = Array.Find(points, ProductGT10);
        // Note that you do not need to create the delegate 
        // explicitly, or to specify the type parameter of the 
        // generic method, because the C# compiler has enough
        // context to determine that information for you.
        // Display the first structure found.
        Console.WriteLine("Found: X = {0}, Y = {1}", first.X, first.Y);
    }
    // This method implements the test condition for the Find
    // method.
    private static bool ProductGT10(Point p)
    {
        if (p.X * p.Y > 100000)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}
/* This code example produces the following output:
Found: X = 275, Y = 395
 */

传统字体:

foreach (int number in numArray) { if (number < 0) return true; }
return false;
用LINQ

: 

bool result = numArray.Any(x => x < 0);

稍微扭曲的版本是

public static bool AnyNegative(int[] arr){
  const long firstBit = 2147483648;
  var res = false;
  for (var i = 0; i < arr.Length && !res; i++) res = (arr[i] & firstBit) == firstBit;
  return res;
}

你可以这样称呼它>

int arr = {...}
  if(arr.AnyNegative()){
      //do stuf if there's any negative numbers
  }

当然这只是

的混淆版本
public static bool AnyNegative(int[] arr){
            var res = false;
            for (var i = 0; i < arr.Length && !res; i++) res = arr[i] < 0;
            return res;
}
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