- CB 3.12,3.13 Developing Procedures

What is a procedure?

A procedure is a named group of code that has paramaters and return values. Procedures are known as methods or functions depending on the language.

A procedure executes the statements within it on the parameters to provide a return value.

What are parameters?

Paramaters are input values of a procedure that are specified by arguments.Arguments specify the values of the parameters when a procedure is called.

By creating theses algorithms the readibility of code increases and the complexity decreases. This is becasue a function’s name can tell the reader what action it will perform, and by calling it, the code becomes more clean and easy to understand.

What is a return value?

A return value is the value that is returned when a function or a method is called.

That return value can be assigned or printed

Procedures are used to create algorthims that can perform certain actions or return values. When a procedure returns a value, theis information must be stored in a variable for later use. However some procedures like the MOVE_FORWARD() perform an action, and don’t return a value. The image above provides an example of where procedures that don’t output a value would be used.

A 60$ item recieves a 20% discount and taxed at 8%.
PROCEDURE applyDiscount(cost, percentDiscounted)
{
    temp ← 100 - percentDiscounted
    temp← temp/ 100
    cost ← cost *temp
    RETURN(cost)
}

price ← applyDiscount(60, 20)
This is how we get the final price with the discount by calling the procedure and assigning it to the price variable.


PROCEDURE applyTax(cost, percentTaxed)
{
    temp ← 100 + percentTaxed
    temp← temp/ 100
    cost ← cost *temp
    RETURN(cost)
}
price ← applyTax(price, 8)

This applys the 8% tax to the price determined after the discount.

Popcorn Hack 1

Given the applyTax procedure above: How would you call the procedure to get it to find the price using cost = 50, and percentTaxed = 10, and what value will it return?

def applyTax(cost, percentTaxed):
    temp = 100 + percentTaxed
    temp = temp/ 100
    cost = cost * temp
    return cost 


tax = applyTax(50, 10)
print(tax)

55.00000000000001

What Are Functions?

• Collections of code
• Divides large program into smaller chunks
• Better readability
• Less repetitive code
• More efficient code
• Good organization

What Are The Components of a Function?

• The function declaration
• The parameters (input). This is also referred to as an argument when a value is being passed to the actual function.
• The functionality
• The return value (output)
• Calling the function

# Defining Functions
#
# def function_name(parameter1, parameter2, etc..):
#     code here...
#
#     return return_value;

# return the value of parameter1 plus parameter2;
def add(parameter1, parameter2): # creates a function that takes in two parameters
    solution = parameter1 + parameter2; # sets solution to the sum of parameter1 and parameter2
    return solution; # return solution
    
print(add(5, 5)); # prints the return value of add(5,5)

10

Popcorn Hack 2:

1. Make a function that returns the difference of two numbers

def subtract(number1, number2):
    answer = number1 - number2;
    return answer

print(subtract(6,4))

2

What is a Class?

• A class is an outline for a set of nested functions and variables.
• There are instance variables
• Functions
• Constructor method (Required)
• To String method
• Getter method
• Setter method

How Does a Class Work?

# Defining Classes
class person:
    def __init__(self, name, age, ): # constructor
        self.name = name;
        self.age = age;
    
    def getName(self): # method to create get name
        return self.name;
    
    def getAge(self): # method to create get age
        return self.age;
    
    def setName(self, name): # method to create set name
        self.name = name;
        
    def setAge(self, age): # method to create set age
        self.age = age;
        
    def yearOlder(self): # method to increment age by 1
        self.age += 1;
        
    def __str__(self): # method that returns a string when the object is printed
        return (f"My name is {self.name} and I am {self.age} years old.")

Person1 = person("John Doe", 15);
print(Person1)


print(Person1);

My name is John Doe and I am 15 years old.
My name is John Doe and I am 15 years old.

Popcorn Hack 3:

1. Create a Car class which has the attributes model, vehicle name, and price

2. Create instances of the following cars

• Name: Honda Civic , Model Year: 2018 , Price: $13,000
• Name: Toyota Prius, Model Year: 2023 , Price: $28,000
• Name: Chevrolet Impala, Model Year: 2020 , Price: $22,000

class Car:
    def __init__(self, model, vehicle, price):
        self.model = model; 
        self.vehicle = vehicle;
        self.price = price;
        print("The car model is " + " " + self.model + " " + "The vehicle is a " + self.vehicle + " " "The price is a " +  " "+ self.price)
    
CarAttribute = Car("2018", "Honda Civic", "$13,000")
CarAttribute2 = Car("2023", "Toyota Prius", "$28,000")
CarAttribute3 = Car("2020", "Chevrolet Impala", "$22,000")

print(CarAttribute)
print(CarAttribute2)
print(CarAttribute3)

The car model is  2018 The vehicle is a Honda Civic The price is a  $13,000
The car model is  2023 The vehicle is a Toyota Prius The price is a  $28,000
The car model is  2020 The vehicle is a Chevrolet Impala The price is a  $22,000
<__main__.Car object at 0x7f36c47c3c40>
<__main__.Car object at 0x7f36c47c0df0>
<__main__.Car object at 0x7f36c47c29b0>

Homework:

Assignment 1: How do you use functions?

Create a turtle python function that...

1. Takes a single parameter as the number of sides
2. Outputs a shape corresponding to the number of sides
3. Call the function with the argument being a variable with the user input

Hint:

import turtle

pen = turtle.Turtle()


def shape(sides):

  angle = 360 / sides
  for x in range(sides):
    pen.forward(50)
    pen.right(angle)


numsides = input('How many sides do yoUUUU want in YOUUUURRRR shape?!?!!?!: ')
shape(str(numsides))

Assignment 2:

Create a student class that...

1. Has a constructor that takes three parameters as attributes
2. • email
   • name
   • grade
3. Three getter methods to access the name, email, and grade
4. Three setter methods to modify the name, email, and grade
5. A to string method that returns the three instance variables in this format - "My name is {name}. My email is {email}. My grade is {grade}
6. Create an instance of the class that corresponds with you

class personalInformation:
    def __init__(self, name, email, grade):
        self.name = name;
        self.email = email;
        self.grade = grade;
        
    def getName(self):
        return self.name
    
    def getEmail(self):
        return self.email
    
    def getGrade(self):
        return self.grade
    
    def setName(self):
        self.name = name;
    
    def setEmail(self):
        self.email = email;
        
    def setGrade(self):
        self.grade = grade;
        
    def __str__(self):
        return (f"My name is {self.name}, My email is {self.email} and I am in {self.grade} grade.")
    
information = personalInformation("Nandan", "exampleemail@gmail.com", "11th")
print(information)
    
        

My name is Nandan, My email is exampleemail@gmail.com and I am in 11th grade.