Cogs 18 UCSD midterm terms

name = value

Variables are defined with

=

refers to assignment.

==

refers to equality

Integers

store whole numbers

Floats

store signed, decimal-point numbers.

Strings

store characters, as text

Booleans

store True or False

None

used to denote a null or empty value.

+, -, *, /

addition, subtraction, multiplication, & division

**

exponentiation

%

modulus

//

for floor division (integer division)

!=

values are not equal

<

value on left is less than value or right

>

value on left is greater than value on right

<=

value on left is less than or equal to value on right

>=

value on left is greater than or equal to value on the right

is

True if both refer to the same object

is not

True if they do not refer to the same object

def( )

you are defining a function

Conditionals

statements that check for a condition, using the if statement, and then only execute a set of code if the condition evaluates as True

else

you can use after an if that will run if the conditional(s) above have not run.

elif

After an if statement, you can have any number of else if to check other conditions

list

a mutable collection of ordered items, that can be of mixed type. Created using square brackets. mutable

start:stop

A sequence of indices (called a slice) can be accessed using

start:stop:step

To skip values in a sequence use

tuple

an immutable collection of ordered items, that can be of mixed type. immutable

dictionary

mutable collection of items, that can be of mixed-type, that are stored as key-value pairs.

in

operator asks whether an element is present inside a collection, and returns a boolean answer.

ord

returns the unicode code point for a one-character string

chr

returns the character encoding of a code point.

Errors

problems with code definition or execution that interrupt running Python code.

ZeroDivisionError

occurs when you try to divide by zero.

NameError

occurs when you try to access a name that Python does not know.

IndexError

occurs when you try to access an index that doesn't exist.

ValueError

occurs when you try to use an illegal value for something.

TypeError

occurs when you try to do something with a variable type that python cannot interpret.