问题
It seems to be used in value declarations in the engine but the documentation of JBox-2D does not explain what this 'unit' is. Example:
float x = 20.0f //<-- this 'f'
FixtureDef fixDef = new FixtureDef();
fixDef.shape = shape;
fixDef.density = 0.0f; //<-- this 'f'
fixDef.friction = 0.9f; //<-- this 'f'
What is it? If it is indeed a unit, what is it relative to? What benefit does it have for the engine?
EDIT: What use does it have for the engine? Is there any benefit to using a float opposed to a double?
回答1:
It is no unit, f indicates that the number is a float.
If you just write 0.1 for example, you will get an error because 0.1 will be parsed as a double value. The compiler needs the instruction that the value is desired a float. That's what's the f for.
See http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
回答2:
It indicates that the value is a float literal.
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
来源：https://stackoverflow.com/questions/22180904/what-is-the-f-used-for-in-jbox-2d