Intro to python ch3

Chapter 3. Numbers

Booleans

True or False

Nonzero numbers are True are False

Integers

• Whole numbers

• Literal Integers (can’t have an initial 0 followed by digits 1-9, e.g. 02348), but you can start integer with 0b, 0o, or 0x to indicate the bases

• you can use underscore as a digit separator

Integer operations

operator|description|example|result —-|—-|—–|—-|

• addition

  5+2

  7

• subtraction

  10-7

  3

• mutiplication	20*5	100
  /	floating-point division	10/4	2.5
  //	Integer(truncating) division	7//3
  %	Modulus (remainder)
  **	Exponentiation	3**4	81

divmod(divend,divisor) #returns a tuple containing quotient and remainder

Bases

Integers are assumed base10 you can express literal integers in three bases besides decimal with:

• 0b or oB (base2/binary)
• 0o or 0O (base8/octal)
• 0x or 0X (base16/hex)

you can convert an integer to string with:

value = 65
bin(value)
#outputs in base 2 form
oct(value)
#output in octal
hex(value)
#output in hexadecimal

You can also use char() or ord() to find the string/integer equivalent of something

chr(65)
#returns "A",converts an integer to its single character string equivalent
ord("A")
#retuns "65",converts string to integer equivalent

bases are useful in bit-level operations

int()
#this converts the datatype of the parsed in value to integer
int("10",2) # specifies base 2 
#you can pass in arguments which indicates what base it is in

"""example"""
int("10",8) #octal
int("10",16) # hexadecimal

In Python 2, int are limited to 32 or 64 bits. In Python 3, int could be any size

Floats

floats : short for floating-point number

floats can include decimal integer exponent after letter e

5e0
#5.0
5e1
#50.0
5.0e1
#50.0

when mixing ints and floats, python automatically changes the int to float values