Thread: Creating an INF data type.

I want to create a new data type called an inf_t. It's basically infinity (which for C++ is 1.7e+308). The only reason I want this is because I want to overload the cout << operation to print out INF/inf. Should I do this in a struct?

Code:

struct inf_t {


private:	
	double inf = 1.7e+308;
};


std::ostream& operator << (std::ostream &stream, inf_t inf) {
	
	stream << "INF";


	return stream;
}

Wrong question. Infinity is not represented by a type. It is represented as a special value of a type (particularly a numeric type) if it is represented at all.

The output streaming operators will typically output something like "inf" if a float with an infinite value is passed to it.

The thing is, however, 1.7E308 is not an infinity. It is the maximum finite value that can be represented by some floating point representations (not all implementations have that as a maximum).

If your implementation employs IEEE floating point, there are special values for representing infinities. However, not all implementations work with a floating point type that can represent infinities.

If you look in std::numeric_limits (declared in <limits> you will see the implementation provides has_infinity() to check if a type has a representation for positive infinity, and an infinity() if such a value exists. So, std::numeric_limits<float>::has_infinity() is true if a float can represent an infinity. If that is true, std::numeric_limits<float>::infinity() gives the value of that infinity. Bear in mind that these are compile-time operations (which limits circumstances in which they can be legitimately used without a compiler error/warning).

So, std::numeric_limits<float>::has_infinity() is true if a float can represent an infinity. If that is true, std::numeric_limits<float>::infinity() gives the value of that infinity.

O_o

The `has_infinity' member is a value.

The `infinity()' member is a function.

which limits circumstances in which they can be legitimately used without a compiler error/warning

What does that mean?

Soma

Originally Posted by phantomotap

O_o

What does that mean?

Soma

That you can't check a type that you would get while the program is running, dynamically?¿