Python Basics

A statement of fact it does not tell you have to do stuff

A recipe or “how-to” (this tells you how to do something) Also know as an algorithm

1) A sequence of simple steps 2) Flow of control that specifies when each step is executed 3) Determining when to stop

Is passing of a sentence/string

Is which syntactically valid strings have meaning

Is the meaning associated with syntactically correct string of symbols with no static semantic errors

Is a sequence of definitions and commands • definitions are evaluated • commands are executed

Statements - instruct interpreter to do something

is what the program is manipulating

scalar (cannot be subdivided) non-scalar (have internal structure that can be accessed)

defines what the programs can do to them

• Integers (int) • Real numbers (float) • Boolean (bool) • Special (NoneType)

convert objects of one type to another

** * / \+ and - execute left to right parentheses always have top priority and get done first and will be evaluated inside out.

equal sign is an assignment of a value to a variable name • value stored in computer memory • an assignment binds name to value • retrieve value associated with name or variable by invoking the name

• give names to values of expressions • reuse names instead of values • easier to change code later

• make a choice and do different things • each statement gets executed once • runs in constant time

• name (descriptive, meaningful, re-read code, no keywords) • value (can be updated) • right hand side -> VALUE • left hand side -> VARIABLE

• letters, special characters, spaces, digits • enclosed in quotation marks or single quotes • concatenate strings by using the + operator

is when using the + sign to concatenate two or more strings together

• known number of iterations • can end early via break • use a counter • can rewrite a for loop using while loop

• unbound number of iterations • can end early via break • can use a counter, but must initialize before loop and increment inside loop • may not be able to rewrite a while loop using a for loop

• type(object) returns the type of the object - isinstance(object, type) testing if an object is of a certain type