Python Cheat Sheet Cheat Sheet by pizzajza

1. Forever while loop:
while True: #forever
user_input = input('Enter a number:')
number = int(user_input)
print('The number squared is', number**2)

2. Conditional while loop:
count = 0 # start at zero
while count <10:#loop while count is less than 10
       print (count) #will print numbers 0-9
       count = count + 1 #must increase count

3. Decision making/ conditional statements:
if 3<2: #if statement must compare two booleans
   print('3 is less than 2')
elif 4<2: #can have 0 or more 
    print('4 is less than 2')
elif 5<2:
    print(' 5 is less than 2')
else: #can have 0 or 1 else at the end
    print('none of the above are True')

4. Lists
mylist = [2,3,4,5] #create a list
#select an item from a list
print(mylist[0]) #selects first item and displays 2

#len() determines the length of the list
print(len(mylist)) #displays 4

mylist.append(5) #add an item to the end of the list 
#it will print [2,3,4,5,5]

5. while loop with list:
thelist = [4,3,2,1,0]
index = #start at the first item
while index < len(thelist):
       print(thelist[index]) #prints each item
       index = index + 1

6. for loop with list
forlist = [3,4,5,2,1]
for item in forlist:
     print(item)

7.Range()
#creates a list of numbers from 0 to the specified number]
numberlist = range(5)
#is the same as creating the following list
numberlist2 = [0,1,2,3,4]

for num in range(100):
    print(num) #prints all numbers from 0-99
for num in range(5,50):
    print(num) #prints all numbers from 5-49

8. Functions
#function with no parameters/arguments
#and no return value
#return is optional if you do not return a value
def nameOfFunction():
     print('This function has no parameters')
     print('This function has no return value')
     return #no value, just exits the function
#function call 
nameOfFunction()

#function with 1 parameter/argument
def testFunction(param):
     print('This function has 1 parameter')
     print(param)
#function call
testfunction('this is the parameter value')

#function with 2 parameters and a return value
def function3(param1, param2):
     print('This function has 2 parameters')
     return param1 + param2 #return value
#function call and store the result in a variable
returnValue = function3(2,3)
print(returnValue)

# Practice exam

# 1. Make the loop not to go forever
gameover = 0
while (gameover == 0):
    print("hello")
    gameover = 1 # or break

# 2. Make each number of the list mylist printed out on a seperate line
mylist = [1,2,3,4,5]
for number in mylist:
    print(number)

# 3. Make the program prints out the fifth character from the variable myword
myword = "hellothere"
print(myword[4])

# 4. Write a program that receives input from the user in a loop. Convert the input to an integer and print out that integer multiplied by 10.
while True:
    user_input = input("Please enter a number:")
    user_input1 = int(user_input)
    user_input2 = user_input1*10
    print(user_input2)

# 5. Write a program that uses a while loop to print out each item in the following list:
wlist = [2,4,5,6,7,8]
listnum = 0
while listnum < len(wlist):
    print(wlist[listnum])
    listnum = listnum + 1

# 6. Write a program that uses a for loop to print out each item in the following list:
forlist = ['hi', 'hello', 'goodbye']
for item in forlist:
    print(item)

# Sample Exam 2

# 1. Receive input from the user as a float , and print out half of that number.
user_input = input("Please enter a number:")
print(float(user_input/2))
# 2. What is the putput of the following code:
y = True
print(not y or 2 < 3)
print(True)
# 3. Consider the following code:
message = "hello"
if (len(message)> 5):
    print ("Message is too long")
else:
    print("Message is good")
   # line 3 has an error because there is no indentation.
# 4. Program to receive a number from teh user and determine if that number is divisible by 3.
    # 9 is divisible by 3
    # 7 is not divisble by 3
user_input = input("Please enter a number;")
if user_input%3 == 0:
    print(user_input, "is divisible by 3")
else:
    print(user_input, "is not divisible by 3")
# 5. Print all the even numbers from 1 to 100 using a while loop
num = 2
while num <= 100:
    print(num)
    num = num + 2
# 6. What is the output of the following code:
condition = True
number = 5

if condition == False:
    number = number ** 2
elif number < 5:
    number = number * 2
elif condition == true:
    number = number % 2
else:
    number = number /2
    print(number)
# 7 . Given a list called mylist, print all the elements  from the list using a loop
      #for loop solution            
       mylist = [ 1,2,3,4,5]         
       for number in mylist:         
           print(number)
       #while loop solution
       mylist = [1,2,3,4,5]
       num = 0
       while num < len(mylist)
           print(mylist[num])
           num = num + 1
# 8. Use a for loop a print the following
     #0
     #01
     #012
     #0123
     #01234
mystring = ""
for number in range[5]: #[0,1,2,3,4,5]
     mystring = mystring +str(number)
     print(mystring)
# 9. Write a function called multiplicationTable that asks the user for a user for a number and computes its multiplication table. example: If the users enters 5, the output should be
     # Enter a number: 5
     # 5*1 = 5
     # 5*2 = 10
     def multiplicationTable():
         user_input = input("Enter a number:")
         num = int(user_input)
         count = 1
         while count <= 10:
             print(num, "", count, "=", numcount)
             count = count+1
        #function call
        multiplicationTable()

# Sample Exam 3
#1. Write a program that receives input from the user, converts it to an integer, and prints the product of the integer and 5
user_input = input("Enter a number:")
user_input = int(user_input)
print(user_input*5)
#2. What is the output of the following code:
x = False
print(x and True or 1==1)
      #output is True
#3. no indentation
#4. Write a program that receives a number from the user and determines if that number is zero or positive
    #output of the program
    #4 is positive, 0 is zero, -8 is negative
user_input = int(input("enter a number:"))
if user_input>0:
    print(unser_input, "is positive")
elif user_input<0:
    print (user_input, "is negative")
else:
    print(user_input, "is zero")
#5. Write a program that prints all the even numbers from -100 to -1 using while loop
mynum = -100
while mynum <-1:
    print(mynum)
    mynum = mynum +2
#7. Given a list called mylist, write a program that prints all the items in the list using a loop
mylist = ['cokezero', 'bacon', 'pepsi']
for item in mylist:
    print(item)
#8. Complete the program below by filling in the blank:
        #Expected output of the program:
        #0
        #01
        #012
        #0123
        #01234
mystring =""
count = 0
while count < 5:
       mystring = mystring + str(count)
       print(mystring)
       count = count + 1
#9. Write a unction called areaOfEllipse() that computes the area of an ellipse using the equation: pirr
    #The function should be given two parameterss( radius 1 and radius2) and should return the area
def areaOfEllipse(radius1, radius2):
        pi = 3.1415
        area = piradius1radius2
        return area
    #function call
    area1 = areaOfEllipse(2,3)
    print(area1)
#11.Wrie a program that repeatly receives positive integers from the user. When the user enters a negative integer, exit the loop and orint how many of the numbers entered were even and odd.
evenCount = 0
oddCount = 0
while True:
       num = int(input("Enter a positive integer:"))
       if num < 0 :
         print("Even numbers:", evenCount)
         print("Odd numbers:", oddCount)
         break
       else:
            if(num%2) == 0
                evenCount = evenCount + 1
            else:
                oddCount = oddCount + 1

Rule for giving name 
- letter 
- number (number cannot be the first letter)
- underscore_
- can start with letters or underscores ONLY
- no spaces

Valid name 
- myStr
- my3
- Hello_there

Invalid name 
- 3my = "hi" (cannot start with number)
- first name = "hi" (no spaces allowed)
- first-name (dashes are not accepted)

#Ask the user for a radius of a circle

while True:
    user_radius = input("Please enter the radius of the circle:")
    radius = float(user_radius)
    pi = 3.1415
    area = (piradius*2)
    print("The area of the circle is", area)

#write a function

#name : areaOfTriangle
#parameters : base height
#return : area

user_base = float(input('Enter the base of the triangle:'))
user_height = float(input('Enter the height of the triangle:'))
def areaOfTriangle (base, height):
    return 1/2 user_base user_height

#function call
print('The area of the triangle is',areaOfTriangle (user_base, user_height))


#write function compute volume of prism

#name : volumeOfPrism
# parameters : b,h,prism_height
# return volume

def volumeOfPrism(base, height, prism_height):
    # area* prism_height
    volume = areaOfTriangle(base,height) * prism_height

    return volume

user_prism_height = float(input('Enter the prism height:'))
print ('The volume of the prism is', volumeOfPrism(user_base, user_height, user_prism_height))

user_number = ' ' 

while user_number != '0' :
   user_number = input ("Enter a number to convert to binary")
   number = int(user_number)
   binary_string = ' '

while (number > 0):
   remainder = number%2
   binary_string = str(remainder) + binary_string
   number = number // 2

   print ("Binary string is", binary_ string)

user_number = input("What number do you want to count down?")
number = int(user_number)
countdown_string = ' '

while number > 0:
   countdown_number = countdown_string + str(number) + " "
   number = number - 1
   #print (number)

   print (countdown_string)

def calc(num1, num2, operation):
    #use if/elif/else to check what operation to do
    #call the correct function and return the answer
    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):
    #calculate the sum of a and b
    #return the answer
    return a+b

def product(a,b):
    #calculate the product of a and b
    #return the answer
    return a*b

def diff(a,b):
    #calculate the difference between a and b
    #return the answer
    return a-b

def div(a,b):
    if b != 0:
        return a//b
    else:
        print("Error")
    #calculate the division of a and b
    #return the answer
    

print(calc(10,0,"div")) #division by zero 
print(calc(1,2,"sum")) #output should be 3
print(calc(4,2,"diff"))#output should be 2
print(calc(9,3,"div"))#output should be 3
print(calc(2,12,"product"))#output should be 24

_var1 = 1
_var1 = 3
_var1 + 100
print(_var1)

def bacon():
    print("hello")
    return
bacon()

#anything after return will not be printed
def bacon():
    print("hello")
    print("line1")
    return
    print("bye")
bacon()

def myprint(text):#
    print("" + str(text) + "")
    return #return exits the function
myprint(1)
myprint(2.5)
myprint("hello")

def myprint2 (text, decoration): #text and decoration are arguments(parameter) to the function (something you're giving to the function)
    print(decoration + text + decoration)
    return
myprint2("hello", "+++")
myprint2("hello", "-=-=-=-=-=-")
myprint2("hello", ">>>>>>>")

def doubleIt(number):
    return number*2 #return value
print (doubleIt(2))
myvar = doubleIt(doubleIt(3)) #same as doubleIt(6) because doubleIt(3) ==6)
print (myvar) #it will display 12

def areaOfCircle (r):
    if r <= 0:
            return "Error: invalid radius"
    pi = 3.1415
    area = pir*2
    return area
user_radius = input("Enter the radius:")
radius = float(user_radius)
print("The area of the circle is", areaOfCircle(radius))

# write a function that returns the largest of two values
# name: max2
# arguments: num1, num2
# return: the largest value

def max2(num1, num2):
    if num1 > num2:
        maxvalue = num1
    elif num2 > num1:
        maxvalue = num2
    return maxvalue

print(max2(2656,3))

def max2(num1, num2):
    maxvalue = num1
    if num2 > maxvalue:
        maxvalue = num2
    return maxvalue
print(max2(2,3))


# write a function that returns the largest of three values
# name: max3
# arguments: num1, num2, num3
# return: the largest value

def max3(num1, num2, num3):
    maxvalue = num1
    if num2 > maxvalue:
        maxvalue = num2

    if num3 > maxvalue:
        maxvalue = num3
    return maxvalue
print(max3(2,3,4))

# write a function that returns the largest number in a list
# name: maxlist
# arguments: list
# returns the largest value in the list

def maxlist(list):
    maxvalue = list[0]
    for item in list:
        if item > maxvalue:
            maxvalue = item
    return maxvalue
        
mylist = [23,4342,468,56,7873]
print(maxlist(mylist))

firstname = input("What is your first name?")
lastname = input("what is your last name?")

fullname = firstname + " " + lastname
print (fullname)

letternumber = int(input("What is the letter number?"))

if letternumber >= len(fullname):
    print("Invalid letter number,try again.")
else:
    print(fullname[letternumber])
    #letter number is a string
    times = int(input("How many times to print the letter"))
    if times > 100:
        print ("Too many letters to print!")
    else:
        print (fullname[letternumber]*times)
    #square brackets select a letter inside a string

#how to create a function
def nameOfFunction (myvar1, myvar2):
    print("hello")
    return myvar1 + myvar2

#function call
nameOfFunction (2,3)
myanswer = nameOfFunction (4,1)
print(myanswer)
print(nameOfFunction(nameOfFunction(2,1),4))
# it will print(nameOfFunction(3,4))

while True:
   word = input('Please enter a word')
   index = 0
   reverse = ''

   while int(index) < len(word):
         reverse = word[index] + (reverse)
         index = int(index) + 1

   print ("Reverse: ", reverse)