变量和命名

cars = 100

space_in_a_car = 4.0

drivers = 30

passengers = 90

cars_not_driven = cars - drivers

cars_driven = drivers

carpool_capacity = cars_driven * space_in_a_car

average_passengers_per_car = passengers / cars_driven

print "There are", cars, "cars available."

print "There are only", drivers, "drivers available."

print "There will be", cars_not_driven, "empty cars today."

print "We can transport", carpool_capacity, "people today."

print "We have", passengers, "to carpool today."

print "We need to put about", average_passengers_per_car, "in each car."

打印得出：

There are 100 cars available.
There are only 30 drivers available.
There will be 70 empty cars today.
We can transport 120.0 people today.
We have 90 to carpool today.
We need to put about 3 in each car.

= 的名字是等于 (equal)，它的作用是为东西取名。

_ 是下划线字符 (underscore)。

将 python 作为计算器运行起来，就跟以前一样，不过这一次在计算过程中使用变量名来做计算，常
见的变量名有 i, x, j 等等。