Ⅰ. Operator(运算符) 1. Assignment operator (赋值运算符) Simple assignment operators: = Compound assignment operators: +=, -=, *=, /= %=, **=, //= 2. Identifier (标识符) a) An identifier is a name given to a variable, function, class or module. b) be a combination of: letters in lowercase (a to z) or uppercase (A to Z),  numbers (0 to 9) , underscores( _ ). c) must start with a letter or an underscore, and cannot start with a number ! d) cannot be “language reserved words” (keywords). 3. Arithmetic operators (算术运算符) +,-,*,/ % # remainder 取模(取余) ** # exponentiation 幂 // # floor division 取整 4.Comparison operators (比较运算符) ==,!=,>,<,>=,<= 5.Logical operators (逻辑运算符) and & or | not …………

Ⅱ. Basic data types #type() 1. Boolean （布尔值） Ture False 2. Integer（整型） 3. Float （浮点数） ⅰ) 取整 a.四舍五入 round() eg. b.向上/下取整 math.ceil() math.floor() eg. ⅱ)Convert between int and float int() float() 4. String（字符串） immutable  ordered ⅰ) Basics a. +.* b. in not in ⅱ) Built-in functions a. len() b. ⅲ) Index str[] ⅳ) Slicing string_x [start: stop: step] a) positions are inclusive at the start, but exclusive at the stop. b) step can be specified to specify steps in slicing; the default value of step is 1. ⅴ) String methods # All string methods returns new values. They do not change the original string. a) lower() ,upper() string.lower() string.upper() b> replace() string.replace(oldvalue, newvalue, count) c) count() string.count(value, start, end) d) find() string.find(value, start, end) e) split() string.split(separator, maxsplit) f) startswith(), endswith() string.startswith(value, start, end) string.endswith(value, start, end) g) strip() string.strip(characters) ⅵ) Conversion between data types str() int() float()

Print formatting 1. Using the Modulo Operator: *% ‘d’ : *integer. ‘f’ or ‘F’ : Float. ‘s’ : String. 2. Using the format() function 3. Using f-Strings