Vocabulary
variable |
something that can change |
string |
a list of characters |
integer number |
pos/neg natural numbers and zero |
floating point |
decimal number |
length |
the length of the string |
Modulo |
Finds the remainder |
Boolean |
True/False |
Syntax |
Grammar/Structure of language |
range (1,10) |
the numbers 1-9 |
range(10) |
the numbers 0-10 |
Conditionals
If..... :then..... else....... |
If the statement is true then do command under then else do command under else |
while...... |
While this is true loop the command under the conditional |
While True |
loops forever |
for each item in name of list |
For every item in the list repeat the command under the loop that many times. (a string is a list too) |
Naming Conventions
Rules for naming variables:
- letters
- numbers
- underscores (_)
- can start with letters or underscores ONLY
- NO SPACES
Valid names:
- _mystr
- my3
Hello_there
Invalid names:
- 3my= "hi" -- cannot start with number
- first name = "hi" -- no spaces allowed
- first-name -- dashes are not accepted |
Lists
#this is how you maek a list in python
shoppinglist = ['coke zero', 'bacon', 'water', 'jelly', 'gummy bears']
print (shoppinglist)
print (shoppinglist[0])
#prints the first item of the list
list_num = 0
while list_num < len(shoppinglist):
print ("List:", shoppinglist[list_num])
list_num =list_num+1
#for loop--> same as the above
#For every item in that list we're going to print it.
for item in shoppinglist:
print (item)
numbers = range(1,5)
#print up until less then the last number.
for item in numbers:
print (item)
# a string is a list of characters, letters, numbers, etc.
mystr = "hello"
for letter in mystr:
print (letter)
|
Adding strings number
mystring = ""
count = 0
while count < 5:
mystring = mystring + str(count)
print (mystring)
count = count + 1
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Symbols
== |
equal to |
!= |
not equal to |
< |
less than |
<= |
less than or equal to |
> |
greater than |
>= |
greater than or equal to |
+ |
add |
- |
subtract |
* |
multiply |
/ |
divide and quotient is float |
// |
divide and quotient is integer |
** |
exponent |
% |
modulo: the remainder |
[...] |
The position of the item in the list or the letter in a word |
Multiplication & Exponents
string * string |
CRASH!!! |
string * number |
combines the strings multiple time |
number * number |
math (multiply) |
string ** number |
CRASH!!! |
number ** number |
Exponent(Math) |
string ** number |
CRASH!!! |
Even/odd using counters
even_value = 0
odd_value = 0
while True:
user_input = input("Enter a positive number: ")
number = int(user_input)
if number < 0:
print ("There were ", even_value ,"even numbers and there were " , odd_value ,"odd numbers.")
break
if number % 2 == 0:
even_value = even_value + 1
else:
odd_value = odd_value +1
|
Addition
string + string |
squishes them together |
string + number |
crash |
number + number |
math(addition) |
Area of circle
def areaofCircle(r):
if r <= 0:
return "Error: invalid radius"
pi = 3.1415
area = pi(r*2)
return (area)
user_radius = input('Enter the radius: ')
radius = float(user_radius)
print("The area of the circle is", areaofCircle(radius))
|
fibonacci
num1= 0
num2=1
mystr = '0'
while num1 + num2 < 89:
Fibonacci = num1 +num2
num1= num2
num2=Fibonacci
mystr= mystr+"," + str(num1)
print (mystr)
|
Functions
def calc(num1, num2, operation):
if operation == "sum":
return sum(num1, num2)
elif operation == "product":
return product(num1, num2)
elif operation == "diff":
return diff(num1, num2)
elif operation == "div":
return div(num1, num2)
def sum(a, b):
return a+b
def product(a, b):
return a*b
def diff (a, b):
return a-b
def div(a, b):
if b == 0:
return ("Error")
elif b != 0:
return a/b
print (calc(1,2,"sum"))
print (calc(4,2, "diff"))
print (calc (9,0, "div"))
print (calc (2,12, "product"))
calc(1, 2, "sum")
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Functions
print() |
displays information on the screen |
input() |
receives info from the user |
int() |
converts the value into an integer |
str() |
converts the value to a string |
float() |
converts the value to a floating point |
len() |
The length of the string |
# |
One line comment not include in code |
''' |
Multi-line comment |
def name(variable): |
defines a block as in subbing the name for lines of commands. The variable in the parentheses can be replaced by inputing the desire value into those parentheses. |
range (100) |
range of numbers from 0 to one less then that. |
Spelling a string out in reverse code
word = input("Type in an word: ")
reverse = ""
for letter in word:
reverse = letter + reverse
print ("Reverse: ", reverse)
|
This prints the true or false value using boolean
print(True)
print (2<3)
print (2 != 2)
|
Countdown Code
user_number = input("Please enter a number: ")
number = int(user_number)
countdown_string = ""
while number > 0:
countdown_string = countdown_string + " " + str(number)
number = number-1
print (countdown_string)
|
palindrome and efficient loops
def isPalindrome(word):
letter_num =0
while letter_num < len(word)-1-letter_num:
if word[letter_num] == word[len(word)-1-letter_num]:
letter_num = letter_num +1
else:
return False
return True
while True:
user_input = input("Please type in a word: ")
if user_input == "quit":
break
#print (isPalindrome(user_input))
myvalue = isPalindrome(user_input)
if myvalue == True:
print (user_input + " is a palindrome.")
elif myvalue == False:
print (user_input + " is not a palindrome.")
|
list loops #2
word = input("Type in an word: ")
reverse = ""
for letter in word:
reverse = letter + reverse
"""
letter_num = 0
reverse = ''
while letter_num < len(word):
reverse = (word[letter_num] + reverse)
letter_num = letter_num + 1
"""
print ("Reverse: ", reverse)
|
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