So what do you do if you want to divide 45 by 60 and get 0.75? Or if you want to store 3.14159? In C++, the answer is to use floating-point numbers, which represent values with decimal places. In C++, the default floating-point type is called double, which is short for “double-precision”. You can create double variables and assign values to them the same way we did for ints:
When printed, floating point values will be printed rounded to six significant digits. If the value is very large or small, it will be printed in scientific notation like 3.12345e+12 indicating \(3.12345 \times {10}^{12}\text{.}\) (We will learn how to change that formatting later.)
All the operations we have seen—addition, subtraction, multiplication, and division—work on floating-point values, although you might be interested to know that the underlying mechanism is completely different. In fact, most processors have special hardware just for performing floating-point operations. It generally takes longer to perform a given calculation using floating point hardware — 1/3 is quicker to compute than 1.0/3.0. That is one of the reasons why we have two different basic numeric types.
If you store the value 1,500,000 in a double, how will it be printed? (You can use Listing 4.1.1 to check by setting a variable to 1500000 and printing it.)
