Is there a "between" function in C#?

Google doesn't understand that "between" is the name of the function I'm looking for and returns nothing relevant.

Ex: I want to check if 5 is between 0 and 10 in only one operation

It isn't clear what you mean by "one operation", but no, there's no operator / framework method that I know of to determine if an item is within a range.

You could of course write an extension-method yourself. For example, here's one that assumes that the interval is closed on both end-points.

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;
}

And then use it as:

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

No, but you can write your own:

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

Here's a complete class.

/// <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);
    }
}

plus some unit test code

[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));

    }
}

Nope, you'll have to test each endpoint individually.

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

Or if you want it to look more "betweeny", reorder the args:

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

So far, it looks like none of the answers have considered the likely possibility that dynamically, you don't know which value is the lower and upper bound. For the general case, you could create your own IsBetween method that would probably go something like:

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

There is no built in construct in C#/.NET, but you can easily add your own extension method for this:

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

Which can be used like:

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

As of c# 9, you can do 5 is > 0 and < 10; https://docs.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-9#pattern-matching-enhancements

Wouldn't it be as simple as

0 < 5 && 5 < 10

?

So I suppose if you want a function out of it you could simply add this to a utility class:

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

Except for the answer by @Ed G, all of the answers require knowing which bound is the lower and which is the upper one.

Here's a (rather non-obvious) way of doing it when you don't know which bound is which.

  /// <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);
  }

Note: This is NOT a generic method; it is pseudo code. The T in the above method should be replaced by a proper type, "int" or "float" or whatever. (There are ways of making this generic, but they're sufficiently messy that it's not worth while for a one-line method, at least not in most situations.)

Generic function that is validated at compilation!

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

int val_to_check = 5
bool in_range = Enumerable.Range(0, 13).Contains(val_to_check);

The second parameter is the "count" not the end or high number.

I.E.

int low_num = 0
int high_num = 12
int val_to_check = 5
bool in_range = Enumerable.Range(low_num , high_num - low_num + 1).Contains(val_to_check);

Checks if the val_to_check is between 0 and 12

What about

somenumber == Math.Max(0,Math.Min(10,somenumber));

returns true when somenumber is 5. returns false when somenumber is 11.

As @Hellfrost pointed out, it is literally nonsense to compare a number to two different numbers in "one operation", and I know of no C# operator that encapsulates this.

between = (0 < 5 && 5 < 10);

Is about the most-compact form I can think of.

You could make a somewhat "fluent"-looking method using extension (though, while amusing, I think it's overkill):

public static bool Between(this int x, int a, int b)
{
    return (a < x) && (x < b);
}

Use:

int x = 5;
bool b = x.Between(0,10);

Refer to this link. A one line solution to that question.

https://stackoverflow.com/questions/3188672/how-to-elegantly-check-if-a-number-is-within-a-range

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

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

I know the post is pretty old, but It may help others..

I don't know that function; anyway if your value is unsigned, just one operation means (val < 11)... If it is signed, I think there is no atomic way to do it because 10 is not a power of 2...

Base @Dan J this version don't care max/min, more like sql :)

public static bool IsBetween(this decimal me, decimal a, decimal b, bool include = true)
{
    var left = Math.Min(a, b);
    var righ = Math.Max(a, b);

    return include
        ? (me >= left && me <= righ)
        : (me > left && me < righ)
    ;
}

Or if you want to bound the value to the interval:

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

It is like two-sided Math.Min/Max

And for negatives values:

    Public Function IsBetween(Of T)(item As T, pStart As T, pEnd As T) As Boolean ' https://msdn.microsoft.com/fr-fr/library/bb384936.aspx
    Dim Deb As T = pStart
    Dim Fin As T = pEnd
    If (Comparer(Of T).Default.Compare(pStart, pEnd) > 0) Then Deb = pEnd : Fin = pStart
    Return Comparer(Of T).Default.Compare(item, Deb) >= 0 AndAlso Comparer(Of T).Default.Compare(item, Fin) <= 0
End Function