关于优雅，最接近数学符号(a <= x <= b)的方法略微提高了可读性:

public static bool IsBetween(this int value, int min, int max)
{
    return min <= value && value <= max;
}

为了进一步说明:

public static bool IsOutside(this int value, int min, int max)
{
    return value < min || max < value;
}

如果你想写更多的代码而不是简单的If，也许你可以: 创建一个名为IsBetween的扩展方法

public static class NumberExtensionMethods
{
    public static bool IsBetween(this long value, long Min, long Max)
    {
        // return (value >= Min && value <= Max);
        if (value >= Min && value <= Max) return true;
        else return false;
    }
}

...

// Checks if this number is between 1 and 100.
long MyNumber = 99;
MessageBox.Show(MyNumber.IsBetween(1, 100).ToString());

Addendum: it's worth noting that in practice you very rarely "just check for equality" (or <, >) in a codebase. (Other than in the most trivial situations.) Purely as an example, any game programmer would use categories something like the following in every project, as a basic matter. Note that in this example it (happens to be) using a function (Mathf.Approximately) which is built in to that environment; in practice you typically have to carefully develop your own concepts of what comparisons means for computer representations of real numbers, for the type of situation you are engineering. (Don't even mention that if you're doing something like, perhaps a controller, a PID controller or the like, the whole issue becomes central and very difficult, it becomes the nature of the project.) BY no means is the OP question here a trivial or unimportant question.

private bool FloatLessThan(float a, float b)
    {
    if ( Mathf.Approximately(a,b) ) return false;
    if (a<b) return true;
    return false;
    }

private bool FloatLessThanZero(float a)
    {
    if ( Mathf.Approximately(a,0f) ) return false;
    if (a<0f) return true;
    return false;
    }

private bool FloatLessThanOrEqualToZero(float a)
    {
    if ( Mathf.Approximately(a,0f) ) return true;
    if (a<0f) return true;
    return false;
    }

新花样的老最爱:

public bool IsWithinRange(int number, int topOfRange, int bottomOfRange, bool includeBoundaries) {
    if (includeBoundaries)
        return number <= topOfRange && number >= bottomOfRange;
    return number < topOfRange && number > bottomOfRange;
}

我会创建一个Range对象，就像这样:

public class Range<T> where T : IComparable
{
    public T InferiorBoundary{get;private set;}
    public T SuperiorBoundary{get;private set;}

    public Range(T inferiorBoundary, T superiorBoundary)
    {
        InferiorBoundary = inferiorBoundary;
        SuperiorBoundary = superiorBoundary;
    }

    public bool IsWithinBoundaries(T value){
        return InferiorBoundary.CompareTo(value) > 0 && SuperiorBoundary.CompareTo(value) < 0;
    }
}

那么你可以这样使用它:

Range<int> myRange = new Range<int>(1,999);
bool isWithinRange = myRange.IsWithinBoundaries(3);

这样你就可以在其他类型中重用它。

只是为了增加这里的噪音，你可以创建一个扩展方法:

public static bool IsWithin(this int value, int minimum, int maximum)
{
    return value >= minimum && value <= maximum;
}

这样你就能做…

int val = 15;

bool foo = val.IsWithin(5,20);

话虽如此，当检查本身只有一行时，这样做似乎是一件愚蠢的事情。

这些是一些可以提供帮助的扩展方法

  public static bool IsInRange<T>(this T value, T min, T max)
where T : System.IComparable<T>
    {
        return value.IsGreaterThenOrEqualTo(min) && value.IsLessThenOrEqualTo(max);
    }


    public static bool IsLessThenOrEqualTo<T>(this T value, T other)
         where T : System.IComparable<T>
    {
        var result = value.CompareTo(other);
        return result == -1 || result == 0;
    }


    public static bool IsGreaterThenOrEqualTo<T>(this T value, T other)
         where T : System.IComparable<T>
    {
        var result = value.CompareTo(other);
        return result == 1 || result == 0;
    }