Checking if a floating point value is within a certain range

[xuinkrbin]

Suppose I wanted to check if a given floating point value is within a certain range. What would be Your recommended approach when considering simplicity, speed, portability, etc.?

[firedraco]

Use the standard > and < or (<= and >=) operators?

[Stewbond]

template <typename T>
bool inline IsBetween(T value, T min, T max)
{
  return (value < max) && (value > min);
}

or

template <typename T>
bool inline IsBetween(T value, T range)
{
  return (value < (value + range)) && (value > (value - range));
}

[xuinkrbin]

Thanks; however, aren't such comparisons typically deprecated when it comes to floating point values?

[naraku9333]

@Stewbond how does your second example work? Wont it will always be true if range is positive.

[Lachlan Easton]

aren't such comparisons typically deprecated when it comes to floating point values?

No. What gave you that impression?

RE Stewbond's second example: naraku is right, you would need to provide a midpoint for the range as well.

[xuinkrbin]

What gave you that impression?

I thought floating point comparisons was one of those things which should not be done due to the inexactness of representing certain numbers, such as 1/3.

[Daleth]

That's only if you test for equality, i.e. == and !=. That is why checking a range (of acceptable error) is recommended over checking equality (Look at firedraco's suggestion and Stewbond's first example to see how to check a range).