python
python What can be done ？
python Characteristics
（1） Grammar is simple , Easy to learn and use
（2） object-oriented programming
（3） Cross platform , It's portable
（4） Modular development , Rich in functions
（5） It has good expansibility
Data labels ： Variable
Declare variables
- Need to pay attention to ：
The first character cannot be a number ;
The identifier cannot have spaces ;
Identifier cannot be associated with Python The key words are ;
Case sensitive .
Variable name ： Use capital letters , Lowercase letters , Numbers , Underline , Chinese characters and other characters are combined to name .
2. assignment ：python The assignment sign of is equal sign “=” , The purpose of assignment is to associate names with values ., for example ：
The assignment operation does not change any value on the right ：
Operators and Expressions
Operators include ：
One 、 Arithmetic operator ：
The addition operator ：
Running results ：
sum1=107, sum2=22.50
Subtraction operators ：
Running results ：
-45 , 83.5
Be careful , Use alone + It's invalid , It doesn't change the value of the number , for example ：
Running results ：
45 , -83.5
Multiplication operators
Please look at the code. ：
Running results ：
100 , 69.0
/ and // Division operator
/ Means common division , The result calculated by this method is the same as that in mathematics .
// To divide or divide , Keep only the integer part of the result , Give up the decimal part ; The point is to just throw away the fraction , Rather than rounding .
Example ：
Calculation results
23/5 = 4.6
23//5 = 4
23.0//5 = 4.0
25/5 = 5.0
25//5 = 5
25.0//5 = 5.0
12.4/3.5 = 3.542857142857143
12.4//3.5 = 3.0
Two 、 Comparison operator :
3、 ... and 、 Assignment operator ：
