Question

I just wanted some information about this.

float n = 2.99944323200023f

What does the f at the end of the literal do? What is it called? Why is it used?

Answer 1

The f indicates it’s a floating point literal, not a double literal (which it would implicitly be otherwise.) It hasn’t got a particular technical name that I know of – I tend to call it the “letter suffix” if I need to refer to it specifically, though that’s somewhat arbitrary!

For instance:

float f = 3.14f; //Compiles
float f = 3.14;   //Doesn't compile, because you're trying to put a double literal in a float without a cast.

You could of course do:

float f = (float)3.14;

…which accomplishes near enough the same thing, but the F is a neater, more concise way of showing it.

Why was double chosen as the default rather than float? Well, these days the memory requirements of a double over a float aren’t an issue in 99% of cases, and the extra accuracy they provide is beneficial in a lot of cases – so you could argue that’s the sensible default.

Note that you can explicitly show a decimal literal as a double by putting a d at the end also:

double d = 3.14d;

…but because it’s a double value anyway, this has no effect. Some people might argue for it advocating it’s clearer what literal type you mean, but personally I think it just clutters code (unless perhaps you have a lot of float literals hanging around and you want to emphasise that this literal is indeed meant to be a double, and the omission of the f isn’t just a bug.)