CODEWITHSUNDEEP
java
crvineeth99
crvineeth99

Reputation: 377

Why is the letter f used at the end of a float no.?

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?

Upvotes: 22

Views: 26224

Answers (10)

عبدو عيد
عبدو عيد

Reputation: 27

For the new versions of C lang, the conversion from double input to a float variable (assigning operation) is done by the compiler without the 'F'

float fraction1 = 1337;
float fraction2 = 1337.0;
float fraction3 = 1337.0F;
printf("%f, %f, %f", fraction1, fraction2, fraction3);

output(C GNU): 1337.000000, 1337.000000, 1337.000000

Upvotes: 0

Mik378
Mik378

Reputation: 22171

If f is not precised at the end, value is considered to be a double. And a double leads to more bytes in memory than float.

Upvotes: 1

Michael Berry
Michael Berry

Reputation: 72284

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.)

Upvotes: 25

Sumit Desai
Sumit Desai

Reputation: 1760

The default Java type which Java will be using for a float variable will be double. So, even if you declare any variable as float, what compiler has to actually do is to assign a double value to a float variable, which is not possible.So, to tell compiler to treat this value as a float, that 'f' is used.

Upvotes: 6

Marcin Orlowski
Marcin Orlowski

Reputation: 75629

When you write 1.0, it's ambiguous as to whether you intend the literal to be a float or double. By writing 1.0f, you're telling Java that you intend the literal to be a float, while using 1.0d specifies that it should be a double (which is also default if you do not specify that explicitely).

Upvotes: 1

Esailija
Esailija

Reputation: 140220

It means that it's a single precision floating point literal rather than double precision. Otherwise, you'd have to write float n = (float)2.99944323200023; to cast the double to single.

Upvotes: 1

Sunmit Girme
Sunmit Girme

Reputation: 559

In Java, when you type a decimal number as 3.6, its interpreted as a double. double is a 64-bit precision IEEE 754 floating point, while floatis a 32-bit precision IEEE 754 floating point. As a float is less precise than a double, the conversion cannot be performed implicitly.

If you want to create a float, you should end your number with f (i.e.: 3.6f).

For more explanation, see the primitive data types definition of the Java tutorial.

Upvotes: 2

jlordo
jlordo

Reputation: 37813

From the Oracle Java Tutorial, section Primitive Data Types under Floating-Point Literals

A floating-point literal is of type float if it ends with the letter F or f; otherwise its type is double and it can optionally end with the letter D or d.

Upvotes: 1

The Cat
The Cat

Reputation: 2475

You need to put the 'f' at the end, otherwise Java will assume its a double.

Upvotes: 1

Josh Greifer
Josh Greifer

Reputation: 3221

It's to distinguish between floating point and double precision numbers. The latter has no suffix.

Upvotes: 1

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