Python Basic introduction （ A full set of nanny level tutorials ）

Chapter one

Section 7 ： Constant

Constants are data that remains constant throughout the operation , Its value is usually given directly in the command or program . They can be certain quantities and information that do not change with time , It can also be a character or string representing a certain value , Often used to identify 、 Measurement and comparison .
Easy to understand, like in Mathematics pai, The speed of light in a vacuum in Physics с, Planck constant h 、 elementary charge e They're all constants .
You can turn all the letters of variables into uppercase, which can be regarded as constants , But there is no constant in the absolute sense .

PI = 3.1415926
print(PI)
PI = 3
print(PI)