Appendix B

Quick Reference

Table 1 Python input, output, variables

Leaving reminders by using comments

Using constants

# whole-line comment

print("hello") # end-of-line comment

SIZE = 100 # upper case name

Printing to the screen

Reading from the keyboard (Python V3)

print(10) # print a number

print("hello") # print a string

print(a) # print a variable

name = input("your name?")

age = int(input("how old?"))

Storing values in variables

Using Boolean variables

a = 10 # an integer (whole) number

b = 20.2 # a decimal number

message = "hello" # a string

finished = True # a Boolean

high_score = None # no value

anotherGo = True

while anotherGo:

choice = int(input("choice?"))

if choice == 8:

anotherGo = False

Converting strings to (integer) numbers

Converting numbers to strings

size = int(size)

size = size + 1

age = str(age)

print("Your age is " + age)

Calculating with number variables

Calculating absolute values and differences

b = a + 1 # addition

c = a - 1 # subtraction

d = a * 2 # multiplication

e = a / 2 # division

f = a % 2 # remainder after division

absolute = abs(-1) # absolute is 1

difference = abs(x1-x2)

smallest = min(x1, x2)

largest = max(x1, x2)

Table 2 Python loops

Looping

Using counted loops

a = 0

while a<100:

print(a)

a = a + 1

for a in range(10):

print(a) # 0..9

for a in range(5, 50, 5):

print(a) # 5..45 in steps of 5

Looping through all characters in a string

Splitting comma-separated strings

name = "Charlotte"

for ch in name:

print(ch)

line = ...

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