- 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.

  File "/tmp/ipykernel_1599/4034616119.py", line 4
    temp ← 100 - percentDiscounted
         ^
SyntaxError: invalid character '←' (U+2190)

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?

#code here
cost = 50
percentTaxed = 10
applyTax = (cost/percentTaxed) + cost
print(applyTax)

55.0

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)

Popcorn Hack 2:

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

# Code here
def diff(x, y):
    z = x - y
    return z
print(diff(10, 5))

-5

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);

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__(name, year, price, ): 
        self.name = name;
        self.year = year;
    def getName(self): 
        return self.name; 
    def getAge(self): 
        return self.year;   
    def setName(self, name): 
        self.name = name;
print(car)

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
# Function to draw a shape with the specified number of sides
def draw_shape(num_sides):
    angle = 360 / num_sides  # Calculate the angle for each side
    for _ in range(num_sides):
        turtle.forward(100)  # Replace 100 with the desired side length
        turtle.right(angle)
# Get the number of sides from the user
num_sides = int(input("Enter the number of sides for the shape: "))
# Create a Turtle screen and draw the shape
window = turtle.Screen()
turtle.speed(1)  # Adjust the drawing speed if needed
draw_shape(num_sides)
# Close the drawing window when clicked
window.exitonclick()

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 Student:
    def __init__(self, email, name, grade):
        self.email = email
        self.name = name
        self.grade = grade
    def get_name(self):
        return self.name
    def get_email(self):
        return self.email
    def get_grade(self):
        return self.grade
    def set_name(self, name):
        self.name = name
    def set_email(self, email):
        self.email = email
    def set_grade(self, grade):
        self.grade = grade
    def __str__(self):
        return f"My name is {self.name}. My email is {self.email}. My grade is {self.grade}"
# Create an instance of the Student class
student_instance = Student("ashwinkrv@gmail.com", "Ashwin Visvanath", 99)
# Access attributes and print the student's information
print(student_instance)

My name is Ashwin Visvanath. My email is ashwinkrv@gmail.com. My grade is 99