在。net中我可以在哪里找到“clamp”函数?

I would like to clamp a value x to a range [a, b]:

我想将一个值x固定到一个范围[a, b]:

x = (x < a) ? a : ((x > b) ? b : x);

This is quite basic. But I do not see a function "clamp" in the class library - at least not in System.Math.

这是很基本的。但我在类库中看不到“箝位”函数——至少在System.Math中看不到。

(For the unaware to "clamp" a value is to make sure that it lies between some maximum and minimum values. If it’s greater than the max value, then it’s replaced by the max, etc.)

(对于不知道“夹”的值，则要确保它位于某些最大值和最小值之间。如果它大于最大值，那么它就被最大值所代替)

7 个解决方案

#1

You could write an extension method:

你可以写一个扩展方法:

public static T Clamp<T>(this T val, T min, T max) where T : IComparable<T>
{
    if (val.CompareTo(min) < 0) return min;
    else if(val.CompareTo(max) > 0) return max;
    else return val;
}

EDIT: Extension methods go in static classes - since this is quite a low-level function, it should probably go in some core namespace in your project. You can then use the method in any code file that contains a using directive for the namespace e.g.

编辑:扩展方法进入静态类——因为这是一个相当低级的函数，它可能应该进入项目中的一些核心名称空间。然后，您可以在任何包含名称空间使用指令的代码文件中使用该方法。

using Core.ExtensionMethods

int i = 4.Clamp(1, 3);

.NET Core 2.0

Starting with .NET Core 2.0 System.Math now has a Clamp method that can be used instead:

从。net Core 2.0系统开始。Math现在有了一种箝位方法，可以用来代替:

using System;

int i = Math.Clamp(4, 1, 3);

#2

Try:

试一试:

public static int Clamp(int value, int min, int max)  
{  
    return (value < min) ? min : (value > max) ? max : value;  
}

#3

Just use Math.Min and Math.Max:

用数学。最小值和Math.Max:

x = Math.Min(Math.Max(x, a), b);

#4

There isn't one, but it's not too hard to make one. I found one here: clamp

没有，但做一个并不难。我在这里找到一个:钳子

It is:

它是:

public static T Clamp<T>(T value, T max, T min)
    where T : System.IComparable<T> {
        T result = value;
        if (value.CompareTo(max) > 0)
            result = max;
        if (value.CompareTo(min) < 0)
            result = min;
        return result;
    }

And it can be used like:

可以这样使用:

int i = Clamp(12, 10, 0); -> i == 10
double d = Clamp(4.5, 10.0, 0.0); -> d == 4.5

#5

There isn't one in the System.Math namespace

系统中没有。数学名称空间

http://msdn.microsoft.com/en-us/library/system.math_members.aspx

http://msdn.microsoft.com/en-us/library/system.math_members.aspx

There is a MathHelper Class where it is available for the XNA game studio if that happens to be what you are doing:

有一个MathHelper类，它可以用于XNA游戏工作室，如果这恰好是你正在做的事情:

http://msdn.microsoft.com/en-us/library/bb197892(v=XNAGameStudio.31).aspx

http://msdn.microsoft.com/en-us/library/bb197892(v = XNAGameStudio.31). aspx

#6

Just sharing Lee's solution with the comments' issues and concerns addressed, where possible:

只要在可能的情况下，把李的解决方案与评论中提出的问题和关注分享给大家:

public static T Clamped<T>(this T value, T min, T max) where T : IComparable<T> {
    if (value == null) throw new ArgumentNullException(nameof(value), "is null.");
    if (min == null) throw new ArgumentNullException(nameof(min), "is null.");
    if (max == null) throw new ArgumentNullException(nameof(max), "is null.");
    //If min <= max, clamp
    if (min.CompareTo(max) <= 0) return value.CompareTo(min) < 0 ? min : value.CompareTo(max) > 0 ? max : value;
    //If min > max, clamp on swapped min and max
    return value.CompareTo(max) < 0 ? max : value.CompareTo(min) > 0 ? min : value;
}

---

Differences:

差异:

• Method name uses the appropriate verb tense (ed) to (further) indicate that the value is not clamped in-place, and that, instead, a new value is returned (See @JimBalter's comment).
• 方法名使用适当的动词时态(ed)来(进一步)表示该值没有被固定在适当的位置，而是返回一个新的值(参见@JimBalter的注释)。
• Does appropriate null check on all inputs (See @JeppeStigNielsen's comment).
• 对所有输入执行适当的null检查(参见@JeppeStigNielsen的评论)。
• Swaps min and max if min > max (See @JeppeStigNielsen's comment).
• 如果min > max，则交换min和max(见@JeppeStigNielsen的评论)。

Limitations: No one-sided clamps. If max is NaN, always returns NaN (See Herman's comment).

限制:不片面的夹子。如果max是NaN，总是返回NaN(见Herman的评论)。

#7

Using the previous answers, I condensed it down to the below code for my needs. This will also allow you to clamp a number only by its min or max.

使用前面的答案，我将它压缩为下面的代码以满足我的需要。这也将允许您仅通过它的最小或最大值来限制一个数字。

public static class IComparableExtensions
{
    public static T Clamped<T>(this T value, T min, T max) 
        where T : IComparable<T>
    {
        return value.CompareTo(min) < 0 ? min : value.ClampedMaximum(max);
    }

    public static T ClampedMinimum<T>(this T value, T min)
        where T : IComparable<T>
    {
        return value.CompareTo(min) < 0 ? min : value;
    }

    public static T ClampedMaximum<T>(this T value, T max)
        where T : IComparable<T>
    {
        return value.CompareTo(max) > 0 ? max : value;
    }
}