Partial template specialization based on “signed-ness” of integer type?

Question

Given:

template
inline bool f( T n ) {
  return n >= 0 && n <= 100;
}   

When used with an unsigned

Answer 1

Starting in c++17 with the introduction of if constexpr you don't even need to provide specializations for this. Unlike a normal if statement the code in the if constexpr will be discarded (not compiled) if the expression is not true. That means you can rewrite your function like

template
inline bool f( T n ) 
{
    if constexpr (std::is_unsigned_v)
        return n <= 100;
    else
        return n >= 0 && n <= 100;
}