static class ExtensionMethods
{
    internal static bool IsBetween(this double number,double bound1, double bound2)
    {
        return Math.Min(bound1, bound2) <= number && number <= Math.Max(bound2, bound1);
    }

    internal static bool IsBetween(this int number, double bound1, double bound2)
    {
        return Math.Min(bound1, bound2) <= number && number <= Math.Max(bound2, bound1);
    }
}

使用

double numberToBeChecked = 7;

var result = numberToBeChecked.IsBetween（100，122）;

var result = 5.IsBetween（100，120）;

var result = 8.0.IsBetween（1.2，9.6）;

好吧，我会配合的。已经有这么多答案了，但也许还有一些其他新奇的空间:

(显然你根本不用这些)

    var num = 7;
    const int min = 5;
    const int max = 10;
    var inRange = Math.Clamp(num, min, max) == num;

Or

    var num = 7;
    const int min = 5;
    const int max = 10;
    var inRange = num switch { < min => false, > max => false, _ => true };

Or

    var num = 7;
    const int min = 5;
    const int max = 10;
    var inRange = num is >= min and <= max;

好吧，也许你可以用最后一个。

好的，再来一个

    var num = 7;
    const int min = 5;
    const int max = 10;
    var inRange = Enumerable.Range(min, max-min).Contains(num);

我使用下一个“优雅”的解决方案:

using static System.Linq.Enumerable;

int x = 30;
if (Range(1,100).Contains(x))  //true

来自微软文档

using static指令适用于任何具有静态成员(或嵌套类型)的类型，即使它也具有实例成员。但是，实例成员只能通过类型实例调用。

你可以访问一个类型的静态成员，而不需要用类型名限定访问:

但这对许多人来说并不简单，因为Enumerable。Range有第一个参数start和第二个参数count。 所以这种检查可能在特定情况下有用，比如当你使用Enumerable时。范围的foreach循环，在开始之前，您想知道，如果循环将执行。

例如:

        int count = 100;
        int x = 30;

        if (!Range(1, count).Contains(x)) {
            Console.WriteLine("Do nothing!");
            return;
        }

        foreach (var i in Range(1, count)) {
            // Some job here
        }

有很多选择:

int x = 30;
if (Enumerable.Range(1,100).Contains(x))  //true

实际上，基本的，如果更优雅的话，可以在第一张支票中用倒序写:

if (1 <= x && x <= 100)   //true

此外，查看这篇SO帖子的正则表达式选项。

注:

LINQ solution is strictly for style points - since Contains iterates over all items its complexity is O(range_size) and not O(1) normally expected from a range check. More generic version for other ranges (notice that second argument is count, not end): if (Enumerable.Range(start, end - start + 1).Contains(x) There is temptation to write if solution without && like 1 <= x <= 100 - that look really elegant, but in C# leads to a syntax error "Operator '<=' cannot be applied to operands of type 'bool' and 'int'"

如果您关心@Daap对已接受答案的注释，并且只能传递一次值，则可以尝试以下方法之一

bool TestRangeDistance (int numberToCheck, int bottom, int distance)
{
  return (numberToCheck >= bottom && numberToCheck <= bottom+distance);
}

//var t = TestRangeDistance(10, somelist.Count()-5, 10);

or

bool TestRangeMargin (int numberToCheck, int target, int margin)
{
  return (numberToCheck >= target-margin && numberToCheck <= target+margin);
}

//var t = TestRangeMargin(10, somelist.Count(), 5);

Using an && expression to join two comparisons is simply the most elegant way to do this. If you try using fancy extension methods and such, you run into the question of whether to include the upper bound, the lower bound, or both. Once you start adding additional variables or changing the extension names to indicate what is included, your code becomes longer and harder to read (for the vast majority of programmers). Furthermore, tools like Resharper will warn you if your comparison doesn't make sense (number > 100 && number < 1), which they won't do if you use a method ('i.IsBetween(100, 1)').

我要做的唯一另一个评论是，如果你检查输入的意图是抛出异常，你应该考虑使用代码契约:

Contract.Requires(number > 1 && number < 100)

这比if(…)抛出new Exception(…)更优雅，如果有人试图调用您的方法而没有首先确保该数字在边界内，您甚至可以得到编译时警告。