C#中有"之间"功能吗？

Question

谷歌不明白"之间"是我正在寻找的功能的名称,并且没有任何相关内容.

例如:我想在一次操作中检查5是否在0到10之间

Answer 1

目前尚不清楚"一个操作"是什么意思,但是没有,我知道没有运算符/框架方法来确定一个项目是否在一个范围内.

你当然可以自己写一个扩展方法.例如,这里假设间隔在两个端点上都是闭合的.

public static bool IsBetween<T>(this T item, T start, T end)
{
    return Comparer<T>.Default.Compare(item, start) >= 0
        && Comparer<T>.Default.Compare(item, end) <= 0;
}

然后将其用作:

bool b = 5.IsBetween(0, 10); // true

Answer 2

不,但你可以写自己的:

public static bool Between(this int num, int lower, int upper, bool inclusive = false)
{
    return inclusive
        ? lower <= num && num <= upper
        : lower < num && num < upper;
}

Answer 3

这是一个完整的课程.

/// <summary>
/// An extension class for the between operation
/// name pattern IsBetweenXX where X = I -> Inclusive, X = E -> Exclusive
/// <a href="https://stackoverflow.com/a/13470099/37055"></a>
/// </summary>
public static class BetweenExtensions
{

    /// <summary>
    /// Between check <![CDATA[min <= value <= max]]> 
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">the value to check</param>
    /// <param name="min">Inclusive minimum border</param>
    /// <param name="max">Inclusive maximum border</param>
    /// <returns>return true if the value is between the min & max else false</returns>
    public static bool IsBetweenII<T>(this T value, T min, T max) where T:IComparable<T>
    {
        return (min.CompareTo(value) <= 0) && (value.CompareTo(max) <= 0);
    }

    /// <summary>
    /// Between check <![CDATA[min < value <= max]]>
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">the value to check</param>
    /// <param name="min">Exclusive minimum border</param>
    /// <param name="max">Inclusive maximum border</param>
    /// <returns>return true if the value is between the min & max else false</returns>
    public static bool IsBetweenEI<T>(this T value, T min, T max) where T:IComparable<T>
    {
        return (min.CompareTo(value) < 0) && (value.CompareTo(max) <= 0);
    }

    /// <summary>
    /// between check <![CDATA[min <= value < max]]>
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">the value to check</param>
    /// <param name="min">Inclusive minimum border</param>
    /// <param name="max">Exclusive maximum border</param>
    /// <returns>return true if the value is between the min & max else false</returns>
    public static bool IsBetweenIE<T>(this T value, T min, T max) where T:IComparable<T>
    {
        return (min.CompareTo(value) <= 0) && (value.CompareTo(max) < 0);
    }

    /// <summary>
    /// between check <![CDATA[min < value < max]]>
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">the value to check</param>
    /// <param name="min">Exclusive minimum border</param>
    /// <param name="max">Exclusive maximum border</param>
    /// <returns>return true if the value is between the min & max else false</returns>

    public static bool IsBetweenEE<T>(this T value, T min, T max) where T:IComparable<T>
    {
        return (min.CompareTo(value) < 0) && (value.CompareTo(max) < 0);
    }
}

加上一些单元测试代码

[TestClass]
public class UnitTest1
{
    [TestMethod]
    public void TestMethodIsBeetween()
    {
        Assert.IsTrue(5.0.IsBetweenII(5.0, 5.0));
        Assert.IsFalse(5.0.IsBetweenEI(5.0, 5.0));
        Assert.IsFalse(5.0.IsBetweenIE(5.0, 5.0));
        Assert.IsFalse(5.0.IsBetweenEE(5.0, 5.0));

        Assert.IsTrue(5.0.IsBetweenII(4.9, 5.0));
        Assert.IsTrue(5.0.IsBetweenEI(4.9, 5.0));
        Assert.IsFalse(5.0.IsBetweenIE(4.9, 5.0));
        Assert.IsFalse(5.0.IsBetweenEE(4.9, 5.0));

        Assert.IsTrue(5.0.IsBetweenII(5.0, 5.1));
        Assert.IsFalse(5.0.IsBetweenEI(5.0, 5.1));
        Assert.IsTrue(5.0.IsBetweenIE(5.0, 5.1));
        Assert.IsFalse(5.0.IsBetweenEE(5.0, 5.1));

        Assert.IsTrue(5.0.IsBetweenII(4.9, 5.1));
        Assert.IsTrue(5.0.IsBetweenEI(4.9, 5.1));
        Assert.IsTrue(5.0.IsBetweenIE(4.9, 5.1));
        Assert.IsTrue(5.0.IsBetweenEE(4.9, 5.1));

        Assert.IsFalse(5.0.IsBetweenII(5.1, 4.9));
        Assert.IsFalse(5.0.IsBetweenEI(5.1, 4.9));
        Assert.IsFalse(5.0.IsBetweenIE(5.1, 4.9));
        Assert.IsFalse(5.0.IsBetweenEE(5.1, 4.9));

    }
}

Answer 4

不,你必须单独测试每个端点.

if ((x > 0) && (x < 10)) {
   // do stuff
}

或者,如果您希望它看起来更"中间",请重新排序args:

if ((0 < x) && (x < 10)) {
   // do stuff
}

Answer 5

从 c# 9 开始，您可以执行5 is > 0 and < 10; https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-9#pattern-matching-enhancements

Answer 6

到目前为止,似乎没有一个答案考虑了动态的可能性,你不知道哪个值是下限和上限.对于一般情况,您可以创建自己的IsBetween方法,该方法可能类似于:

    public bool IsBetween(double testValue, double bound1, double bound2)
    {
        return (testValue >= Math.Min(bound1,bound2) && testValue <= Math.Max(bound1,bound2));
    }

Answer 7

在C#/ .NET中没有内置构造,​​但您可以轻松地为此添加自己的扩展方法:

public static class ExtensionsForInt32
{
    public static bool IsBetween (this int val, int low, int high)
    {
           return val > low && val < high;
    }
}

哪个可以用作:

if (5.IsBetween (0, 10)) { /* Do something */ }

Answer 8

难道不是这么简单吗

0 < 5 && 5 < 10

？

所以我想如果你想要一个函数，你可以简单地将其添加到实用程序类中：

public static bool Between(int num, int min, int max) {
    return min < num && num < max;
}

Answer 9

在编译时验证的通用函数!

public static bool IsBetween<T>(this T item, T start, T end) where T : IComparable
{
    return item.CompareTo(start) >= 0 && item.CompareTo(end) <= 0;
}

Answer 10

除了@Ed G 的答案外，所有答案都需要知道哪个界限是下界，哪个界是上界。

当您不知道哪个界限是哪个时，这是一种（相当不明显的）方法。

  /// <summary>
  /// Method to test if a value is "between" two other values, when the relative magnitude of 
  /// the two other values is not known, i.e., number1 may be larger or smaller than number2. 
  /// The range is considered to be inclusive of the lower value and exclusive of the upper 
  /// value, irrespective of which parameter (number1 or number2) is the lower or upper value. 
  /// This implies that if number1 equals number2 then the result is always false.
  /// 
  /// This was extracted from a larger function that tests if a point is in a polygon:
  /// http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
  /// </summary>
  /// <param name="testValue">value to be tested for being "between" the other two numbers</param>
  /// <param name="number1">one end of the range</param>
  /// <param name="number2">the other end of the range</param>
  /// <returns>true if testValue >= lower of the two numbers and less than upper of the two numbers,
  ///          false otherwise, incl. if number1 == number2</returns>
  private static bool IsInRange(T testValue, T number1, T number2)
  {
     return (testValue <= number1) != (testValue <= number2);
  }

注意：这不是通用方法；它是伪代码。上述方法中的 T 应替换为适当的类型，“int”或“float”或其他类型。（有很多方法可以使这个通用，但它们足够混乱，以至于对于单行方法来说不值得，至少在大多数情况下不是。）