Question

When comparing to a minimum or maximum of two numbers/functions, does C# short-circuit if the case is true for the first one and would imply truth for the second? Specific examples of these cases are

if(x < Math.Max(y, z()))

and

if(x > Math.Min(y, z()))

Since Math.Max(y, z()) will return a value at least as large as y, if x < y then there is no need to evaluate z(), which could take a while. Similar situation with Math.Min.

I realize that these could both be rewritten along the lines of

if(x < y || x < z())

in order to short-circuit, but I think it’s more clear what the comparison is without rewriting. Does this short-circuit?

Answer 1

As others have pointed out, the compiler knows nothing about the semantics of Min or Max that would allow it to break the rule that arguments are evaluated before the method is called.

If you wanted to write your own, you could do so easily enough:

static bool LazyLessThan(int x, int y, Func<int> z)
{
    return x < y || x < z();
}

and then call it

if (LazyLessThan(x, y, z))

or

if (LazyLessThan(x, y, ()=>z()))

Or for that matter:

static bool LazyRelation<T>(T x, T y, Func<T> z, Func<T, T, bool> relation)
{
    return relation(x, y) || relation(x, z());
}
...
if (LazyRelation(x, y, ()=>z, (a,b)=> a < b)))