1. functions: argument, return value
Class 11
printing in columns
functions that print
Unicode
str, chr, ord, int
append
accumulating a string
functions: argument, return value
functions – cooking.

2. printing in columns with titles
#example of printing in columns import math def main(): #print the titles print("{0:<5}{1:>15}{2:>15}".format("angle",\ "sin", "cos")) for ang in range(0,190,30): rad=ang*math.pi/180 print("{0:<5}{1:>15.2f}{2:>15.2f}".format(ang,\ math.sin(rad), math.cos(rad))) main()

3. printing in columns with titles (fixed width font)
angle sin cos

4. Don't call T() in a print statement, there are print statements in T()
def T(): print("-----") print(" | ") def main(): T() # NOT print(T()) – you will get None, the return value.

5. String Representation
In the early days of computers, each manufacturer used their own encoding of numbers for characters.
ASCII system (American Standard Code for Information Interchange) uses 127 bit codes
Python supports Unicode (100,000+ characters)
Python Programming, 3/e

6. String Representation
The ord function returns the numeric (ordinal) code of a single character.
The chr function converts a numeric code to the corresponding character.
>>> ord("A") 65
>>> ord("a") 97
>>> chr(97)
'a'
>>> chr(65)
'A'
Python Programming, 3/e

7. Unicode numerals 0-9 are in order upper case letters are in order
ord('0') is 48, ord('1') is 49,...
ord('4')-ord('0') is 4 – the int
upper case letters are in order
ord('A') is 65
lower case letters are in order
ord('a') is 97
chr(65) is 'A' and chr(97) is 'a'

8. Coding and Encryption
See discussion in the book

9. Building a string accumulate a string First initialize it: message=""
as we go through loop adding characters (or other strings):
message= message + <string>

10. Lists Have Methods, Too
The append method can be used to add an item at the end of a list.
squares = [] for x in range(1,101): squares.append(x*x)
We start with an empty list ([]) and each number from 1 to 100 is squared and appended to it ([1, 4, 9, …, 10000]).
Python Programming, 3/e

11. Lists Have Methods, Too
we can add two lists, but cannot add a list and an int or a string, so need append()
Python Programming, 3/e

12. str vs chr, int vs ord
str to convert a number into a string (so can concat, for exam)
Not the same as chr!
str(65) returns '65'
chr(65) returns 'A'
int('9') returns 9
ord('9') returns 57

13. argument, return value num=ord('K') argument, (or actual parameter)
'K' is a literal
variable num is assigned the return value of the function ord

14. argument, (or actual parameter)
argument, return value
x='T' num=ord(x)
argument, (or actual parameter)
x is a variable

15. functions - cooking