How to elegantly check if a number is within a range?

Question

How can I do this elegantly with C# and .NET 3.5/4?

For example, a number can be between 1 and 100.

I know a simple if would suffice; but the keyword to this

Answer 1

EDIT: New Answer provided. I was just starting out using C# when I wrote the first answer to this question, and in hindsight I now realize that my "solution" was / is naive and inefficient.

My original answer: I'd go with the more simple version:

if(Enumerable.Range(1,100).Contains(intInQuestion)) { ...DoStuff; }

A Better Way

As I haven't seen any other solution that is more efficient (according to my tests at least), I'll give it another go.

New and better way that also works with negative ranges:

// 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);

This can be used with both positive and negative ranges and defaults to a range of

1..100 (inclusive) and uses x as the number to check followed by an optional range defined by min and max.

Adding Examples For Good Measure

Example 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));

Returns:

True
True
True
False
True

Example 2: Using a list of random ints between 1 and 150

// 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();
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);

Returns:

66660 ints found in range 1..100

Execution Time: 0.016 second(s)