Float vs. Double- Comparing both

To have high-precision calculations, it is preferred to use floating points to obtain high accuracy during computation. In many programming languages, floating points or real numbers are represented by two primitive data types i.e. float and double. 

Both of these data types are used to assign and store real values in programming.

They both return decimal values but the precision and accuracy level is the main game changer between them. Besides these similarities, they both have various significant differences. Some of these major differences are explained in this article. 

Float vs. Double: One-to-One Comparison


Variables having float data type can be assigned a value in the range of 1.2×10-38 to 3.4×1038 

Variables having double data type can be assigned a value in the range of 2.3×10-308 to 1.7×10308
It occupies 4 bytes in the memory for storage.

It occupies 8 bytes in the memory for storage.
Precision level
It is a 32-bit floating-point having a single precision.

It is a 64-bit floating-point having a double-precision and is two times more precise than float.
Significant digits precision
It has a precision of 6 to 7 significant digits.

It has a precision of 15 to 16 significant digits. 
A keyword ‘float’ is used to assign this data type to a variable.

A keyword ‘double’ is used to assign this data type to a variable
Where to use it?
Float is used when high accuracy is not needed. It can be useful for smaller computations.

It is used for complex computations for high accuracy in your program. If there is no issue of memory space then double is preferably used. 
Computation Speed
It computes faster as it occupies low memory space.

It takes more time for computation due to higher memory space.
It can store larger values and gives you very precise and highly accurate calculations. 

It is mostly used in graphical libraries to enhance the processing power of the program. Compilers can easily manage float values because they are simple and easy.
It gives us a low precise calculation and rounds off the value if it is out of its range.

It takes a larger space in memory and hence increases the processing time of a program.It is very complicated for compilers to deal with the double values due to their complex structure.

Explanation of Float and Double with Example

To explain the difference between the results of float and double for the same problem, let us take an example in C++. We take two variables a and b having float and double data types respectively. Then we initialize both with the same value to divide 36.4656 by 5.8695. Let’s see the difference between their results.

float a;
double b;
a = 36.4656/5.8695;
b = 36.4656/5.8695;
count << a;
count >> b;

/* output
6.212727 and 6.2127268080756

The results for float and double were 6.212727 and 6.2127268080756 respectively. So, you can see that the float yields the result up to 6 significant figures and then rounds off the answer while double yields the answer up to 13 significant figures and is a more accurate calculation of our given problem.

Should I use Float or Double?

The choice is solely up to you but if you need more accuracy and precision without having any issues of storage space then use double. But if your system is short on memory then go for the float.

Can we compare float and double in C++ ?

Yes, you can compare both of them in C++ but keep the precision factor in mind while doing so as two values can be accurate up to a certain precision level but can be different at different levels of precision.

Why is Float used in C?

 Float is lightweight and fast in speed as compared to double, which is why it is used in C and it is better to use Float instead of double in C to get things done more quickly and accurately.

Is double slower than float?

Yes. Generally speaking, double is slower than float as it requires more memory bandwidth but is more precise than float.

Final words

During the analysis of float vs double, the basic and most important difference we read is the accuracy and precision difference between both.

Concluding the article, I hope that you have come across all the differences between the float and double data types. Considering these differences you can easily choose where you should use your required data types. It all depends on the requirement and need of your program’s result. 

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