Question

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？

如果没有直接方法，即使linq也会这样做。我对linq有点新意。有人可以建议吗？

Answer 1

如果您愿意使用LINQ：

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

或者，如果你想以“老式”的方式做到这一点......你只需要循环：

var containsNegatives = false;

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

如果你真的想要变幻想，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;
    }
}

并从您的代码中调用它，如：

var containsNegatives = numArray.ContainsNegatives();

Answer 2

您可以使用Any：

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

或者

bool containsNegative = numArray.Min() < 0;

<小时/> EDIT

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

Answer 3

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

Answer 4

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
 */

Answer 5

传统：

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

使用LINQ：

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

Answer 6

有点笨拙的版本

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;
}

您可以像这样调用＆gt;

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;
}

C＃，检查整数数组中是否有负数

6 个答案: