Templatized branchless int max/min function

Here's another approach for branchless max and min. What's nice about it is that it doesn't use any bit tricks and you don't have to know anything about the type.

template <typename T> 
inline T imax (T a, T b)
{
    return (a > b) * a + (a <= b) * b;
}

template <typename T> 
inline T imin (T a, T b)
{
    return (a > b) * b + (a <= b) * a;
}

You may want to look at the Boost.TypeTraits library. For detecting whether a type is signed you can use the is_signed trait. You can also look into enable_if/disable_if for removing overloads for certain types.

EDIT: This answer is from before C++11. Since then, C++11 and later has offered make_signed<T> and much more as part of the standard library

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Generally, looks good, but for 100% portability, replace that 8 with CHAR_BIT (or numeric_limits<char>::max()) since it isn't guaranteed that characters are 8-bit.

Any good compiler will be smart enough to merge all of the math constants at compile time.

You can force it to be signed by using a type traits library. which would usually look something like (assuming your numeric_traits library is called numeric_traits):

typename numeric_traits<T>::signed_type x;

An example of a manually rolled numeric_traits header could look like this: http://rafb.net/p/Re7kq478.html (there is plenty of room for additions, but you get the idea).

or better yet, use boost:

typename boost::make_signed<T>::type x;

EDIT: IIRC, signed right shifts don't have to be arithmetic. It is common, and certainly the case with every compiler I've used. But I believe that the standard leaves it up the compiler whether right shifts are arithmetic or not on signed types. In my copy of the draft standard, the following is written:

The value of E1 >> E2 is E1 rightshifted E2 bit positions. If E1 has an unsigned type or if E1 has a signed type and a nonnegative value, the value of the result is the integral part of the quotient of E1 divided by the quantity 2 raised to the power E2. If E1 has a signed type and a negative value, the resulting value is implementation defined.

But as I said, it will work on every compiler I've seen :-p.