像这样的怎么样?

if (theNumber.isBetween(low, high, IntEx.Bounds.INCLUSIVE_INCLUSIVE))
{
}

扩展方法如下(已测试):

public static class IntEx
{
    public enum Bounds 
    {
        INCLUSIVE_INCLUSIVE, 
        INCLUSIVE_EXCLUSIVE, 
        EXCLUSIVE_INCLUSIVE, 
        EXCLUSIVE_EXCLUSIVE
    }

    public static bool isBetween(this int theNumber, int low, int high, Bounds boundDef)
    {
        bool result;
        switch (boundDef)
        {
            case Bounds.INCLUSIVE_INCLUSIVE:
                result = ((low <= theNumber) && (theNumber <= high));
                break;
            case Bounds.INCLUSIVE_EXCLUSIVE:
                result = ((low <= theNumber) && (theNumber < high));
                break;
            case Bounds.EXCLUSIVE_INCLUSIVE:
                result = ((low < theNumber) && (theNumber <= high));
                break;
            case Bounds.EXCLUSIVE_EXCLUSIVE:
                result = ((low < theNumber) && (theNumber < high));
                break;
            default:
                throw new System.ArgumentException("Invalid boundary definition argument");
        }
        return result;
    }
}

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);

使用内置的Range结构体(c# 8+)，我们可以创建一个扩展方法来检查索引是否在原始范围内。

public static bool IsInRangeOf(this Range range, Index index)
{
   return index.Value >= range.Start.Value && index.Value < range.End.Value;
}

由于Index覆盖隐式操作符，因此可以传递int型而不是Index结构体。

var range = new Range(1, 10);
var isInRange = range.IsInRangeOf(1); // true, 1..10 is inclusive min range index(1)
var isInRange = range.IsInRangeOf(10); // false, 1..10 exclusive on max range index (10).
var isInRange = range.IsInRangeOf(100); // false

你在寻找[1..100]?这只是帕斯卡。

编辑:提供了新的答案。 当我写这个问题的第一个答案时，我刚刚开始使用c#，事后我意识到我的“解决方案”是幼稚和低效的。

我最初的回答是: 我会选择更简单的版本:

' if(Enumerable.Range(1100).Contains(intInQuestion)){…DoStuff;} '

更好的方法

因为我还没有看到任何其他更有效的解决方案(至少根据我的测试)，我将再试一次。

新的和更好的方法，也适用于负范围:

// Returns true if x is in range [min..max], else false 
bool inRange(int x, int min=1, int max=100) => ((x - max)*(x - min) <= 0);

这可以用于正负范围，并且默认为

1 . . 100(包括)并使用x作为数字来检查，然后是由min和max定义的可选范围。

为好的措施添加例子

示例1:

// Returns true if x is in range [min..max], else false 
bool inRange(int x, int min=1, int max=100) => ((x - max)*(x - min) <= 0);

Console.WriteLine(inRange(25));
Console.WriteLine(inRange(1));
Console.WriteLine(inRange(100));
Console.WriteLine(inRange(25, 30, 150));
Console.WriteLine(inRange(-25, -50, 0));

返回:

True
True
True
False
True

示例2: 使用100000个1到150之间的随机整数的列表

// Returns true if x is in range [min..max], else false 
bool inRange(int x, int min=1, int max=100) => ((x - max)*(x - min) <= 0);

// Generate 100000 ints between 1 and 150
var intsToCheck = new List<int>();
var randGen = new Random();
for(int i = 0; i < 100000; ++i){
    intsToCheck.Add(randGen.Next(150) + 1);
}

var counter = 0;
foreach(int n in intsToCheck) {
    if(inRange(n)) ++counter;
}

Console.WriteLine("{0} ints found in range 1..100", counter);

返回:

66660 ints found in range 1..100

Execution Time: 0.016 second(s)

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。