python 1 2_Python 1.2

Floats#浮点数

Floats are used in Python to represent numbers that aren't integers.

Some examples of numbers that are represented as floats are 0.5 and -7.8237591.

They can be created directly by entering a number with a decimal point, or by using operations such as division on integers. Extra zeros at the number's end are ignored.

Python中使用浮点数来表示非整数的数字。

一些用浮点数表示的数字的例子是0.5和-7.8237591。

它们可以通过输入带有小数点的数字，或者使用整数除法等操作直接创建。数字末尾的额外零将被忽略。

>>> 3/4

0.75

>>> 9.8765000

9.8765

Computers can't store floats perfectly accurately, in the same way that we can't write down the complete decimal expansion of 1/3 (0.3333333333333333...). Keep this in mind, because it often leads to infuriating bugs!

计算机不能完全准确地存储浮点数，就像我们不能写出1/3(0.3333333333333333……)的完整小数展开式一样。请记住这一点，因为它经常会导致溢出bug !

As you saw previously, dividing any two integers produces a float.

A float is also produced by running an operation on two floats, or on a float and an integer.

如前所述，除任何两个整数都会产生一个浮点数。

浮点数也是通过在两个浮点数或浮点数和整数上运行操作生成的。

>>> 8 / 2

4.0

>>> 6 * 7.0

42.0

>>> 4 + 1.65

5.65

A float can be added to an integer, because Python silently converts the integer to a float. However, this implicit conversion is the exception rather the rule in Python - usually you have to convert values manually if you want to operate on them.

浮点数可以添加到整数中，因为Python会悄悄地将整数转换为浮点数。然而，这种隐式转换是Python中的例外，而不是规则——如果您想对值进行操作，通常必须手动转换值。

Exponentiation#求幂

Besides addition, subtraction, multiplication, and division, Python also supports exponentiation, which is the raising of one number to the power of another. This operation is performed using two asterisks.

除了加法、减法、乘法和除法之外，Python还支持求幂，即将一个数的幂提升到另一个数的幂。此操作使用两个星号执行。

>>> 2**5

32

>>> 9 ** (1/2)

3.0

You can chain exponentiations together. In other words, you can rise a number to multiple powers. For example, 2 3 2.

可以把指数链式。换句话说，你可以把一个数提升到几次方。例如，2,3,2。

Quotient & Remainder# 商和余数

To determine the quotient and remainder of a division, use the floor division and modulo operators, respectively.

Floor division is done using two forward slashes.

The modulo operator is carried out with a percent symbol (%).

These operators can be used with both floats and integers.

要确定除法的商和余数，请分别使用底数除法和模运算符。

Floor division使用两个前斜线。

使用百分号(%)执行模运算符。

这些操作符可以同时用于浮点数和整数。

This code shows that 6 goes into 20 three times, and the remainder when 1.25 is divided by 0.5 is 0.25.

这段代码显示20除以6商为3(余数为2)，1.25除以0.5余数为0.25(商为2).

>>> 20 // 6

3

>>> 1.25 % 0.5

0.25

In the example above, 20 % 6 will return 2, because 3*6+2 is equal to 20.

在上面的例子中，20% 6将返回2，因为3*6+2 = 20。