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c++algorithmmathlogic

Most efficient/elegant way to clip a number?


Given a real (n), a maximum value this real can be (upper), and a minimum value this real can be (lower), how can we most efficiently clip n, such that it remains between lower and upper?

Of course, using a bunch of if statements can do this, but that's boring! What about more compact and elegant/fun solutions?

My own quick attempt (C/C++):

float clip( float n, float lower, float upper )
{
    n = ( n > lower ) * n + !( n > lower ) * lower;
    return ( n < upper ) * n + !( n < upper ) * upper;
}

I'm sure there are other, better ways to do this, that's why I'm putting this out there..!


Solution

  • What about boring, old, readable, and shortest yet:

    float clip(float n, float lower, float upper) {
      return std::max(lower, std::min(n, upper));
    }
    

    ?

    This expression could also be 'genericized' like so:

    template <typename T>
    T clip(const T& n, const T& lower, const T& upper) {
      return std::max(lower, std::min(n, upper));
    }
    

    Update

    Billy ONeal added:

    Note that on windows you might have to define NOMINMAX because they define min and max macros which conflict