# Boolean and Java as not verify the # null value None is a special null # variable variable names must be uppercase and lowercase, numbers and _ in combination, can not start with a number, equal sign = is the assignment statement may the assignment of any data type to a variable, with a variable assignment can be repeated, and may be a different type of variable a = 123 # a is an integer of 123 Print (a) a = ' the ABC ' # a string becomes the ABC Print (a) # for variable assignment x = y x is the variable points to a real object that is pointed to by the variable y. Y is then assigned to the variable the variable x does not affect the point B = ' VV ' A = B A = ' V2 ' Print (A, B) # V2 VV # create a 'ABC' in memory string; #Created in memory of a variable called a and point it 'ABC'. # Above variables are not fixed per se type language called 'dynamic language' is as python, corresponding to the 'static language' as java. Static language must be specified when defining a variable variable type, time assignment if the type does not match, the error will be # constants represent only a constant instructions on the practice of using all uppercase variable names, in fact, still a variable PI PI = 3.14159265359 # division / / floating point division calculations result, even exactly divisible by two integers, floating point result is Print (. 9 /. 3) # 3.0 # // called floor addition, division of two integers is still an integer, discarding directly decimal, unrounded Print (//. 11. 3) # . 3 # remainder Print (10. 3%) # . 1 # Note # integer Python is no size limit, and some languages according integer which memory length is limited in size, e.g. Java scope is limited to 32-bit integer -2147483648-2147483647. # Python floats will no size limit, but beyond a certain range directly expressed as inf (infinity).