FLOW CONTROL
A\The differences between == and = operators:
1 the == operator(equal to) asks whether two values are the same as each other;
2 the = operator(assignment)puts the value on the right into the variable on the left.
B\ Comparison Operator : == != > < >= <=
Boolean Operator : and or not
Boolean Value: Ture False
C\Boolean operators have an order of operations:
1 Math and comparison operators first;
2 not first,then the and,or last;
e.g: not not True or False and not True the result is True
D\Lines of python code can be grouped together in blocks.You can tell when a block begins and ends from the indentation of the lines of code:
1 Blocks begin when the indentation increases;
2 Blocks can contain other blocks;
3 Blocks end when the indentaiton decreases to zero,or to a containing block's indentation;
E\There are some values in other data types （not undefined variable) that conditions will consider equivalent to True and False.When used in conditons,0,0.0 and ' '(the empty string)are considerd False,while all other values are considered True.
e.g
1 name='' 2 while not name: 3 print('enter your name:') 4 name=input() 5 print('how many guests do you have?') 6 numofGuest=int(input()) 7 if numofGuest: 8 print('make sure have enough room.') 9 print('Done!')
F\ if\while contains: 1\keyword (if,while) 2\condition(Boolean Expression) 3\colon 4\clause
for contains: 1\for keyword 2\variable 3\in keyword 4\range()method 5\colon 6\clause
