The Wikipedia page on it is a good place to start.
To sum up:
floatis represented in 32 bits, with 1 sign bit, 8 bits of exponent, and 23 bits of the significand (or what follows from a scientific-notation number: 2.33728*1012; 33728 is the significand).doubleis represented in 64 bits, with 1 sign bit, 11 bits of exponent, and 52 bits of significand.
By default, Java uses double to represent its floating-point numerals (so a literal 3.14 is typed double). It's also the data type that will give you a much larger number range, so I would strongly encourage its use over float.
There may be certain libraries that actually force your usage of float, but in general - unless you can guarantee that your result will be small enough to fit in float's prescribed range, then it's best to opt with double.
If you require accuracy - for instance, you can't have a decimal value that is inaccurate (like 1/10 + 2/10), or you're doing anything with currency (for example, representing $10.33 in the system), then use a BigDecimal, which can support an arbitrary amount of precision and handle situations like that elegantly.
I am learning Java, and am confuse on when to choose double or float for my real numbers or int. It feels like, it doesn’t matter because from my limited experience (with Java) both of them deliver the same results, but I don’t want to go further down the learning curve with Java and have a bad habit of using either messing up my code, and not having a clue as to why. So, when should you use float and double?
floating point - Float and double datatype in Java - Stack Overflow
What's the difference between float , double and long variables?
c++ - When do you use float and when do you use double - Software Engineering Stack Exchange
float vs. double – What's the Key Difference?"
The Wikipedia page on it is a good place to start.
To sum up:
floatis represented in 32 bits, with 1 sign bit, 8 bits of exponent, and 23 bits of the significand (or what follows from a scientific-notation number: 2.33728*1012; 33728 is the significand).doubleis represented in 64 bits, with 1 sign bit, 11 bits of exponent, and 52 bits of significand.
By default, Java uses double to represent its floating-point numerals (so a literal 3.14 is typed double). It's also the data type that will give you a much larger number range, so I would strongly encourage its use over float.
There may be certain libraries that actually force your usage of float, but in general - unless you can guarantee that your result will be small enough to fit in float's prescribed range, then it's best to opt with double.
If you require accuracy - for instance, you can't have a decimal value that is inaccurate (like 1/10 + 2/10), or you're doing anything with currency (for example, representing $10.33 in the system), then use a BigDecimal, which can support an arbitrary amount of precision and handle situations like that elegantly.
A float gives you approx. 6-7 decimal digits precision while a double gives you approx. 15-16. Also the range of numbers is larger for double.
A double needs 8 bytes of storage space while a float needs just 4 bytes.
The default choice for a floating-point type should be double. This is also the type that you get with floating-point literals without a suffix or (in C) standard functions that operate on floating point numbers (e.g. exp, sin, etc.).
float should only be used if you need to operate on a lot of floating-point numbers (think in the order of thousands or more) and analysis of the algorithm has shown that the reduced range and accuracy don't pose a problem.
long double can be used if you need more range or accuracy than double, and if it provides this on your target platform.
In summary, float and long double should be reserved for use by the specialists, with double for "every-day" use.
There is rarely cause to use float instead of double in code targeting modern computers. The extra precision reduces (but does not eliminate) the chance of rounding errors or other imprecision causing problems.
The main reasons I can think of to use float are:
- You are storing large arrays of numbers and need to reduce your program's memory consumption.
- You are targeting a system that doesn't natively support double-precision floating point. Until recently, many graphics cards only supported single precision floating points. I'm sure there are plenty of low-power and embedded processors that have limited floating point support too.
- You are targeting hardware where single-precision is faster than double-precision, and your application makes heavy use of floating point arithmetic. On modern Intel CPUs I believe all floating point calculations are done in double precision, so you don't gain anything here.
- You are doing low-level optimization, for example using special CPU instructions that operate on multiple numbers at a time.
So, basically, double is the way to go unless you have hardware limitations or unless analysis has shown that storing double precision numbers is contributing significantly to memory usage.