- 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?

#code here
cost = 50
DISPLAY applyTax(50, 10)

# return value: 55

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 subtract(num1, num2):
    solution = num1 - num2
    return abs(solution)


subtract(-1, 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);

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, car, model, price): # constructer
        self.car = car
        self.model = model
        self.price = price
    def setCar(self, car):
        self.car = car
    def setCar(self, model):
        self.model = model
    def setPrice(self, price):
        self.price = price
    def getCar(self):
        return self.car
    def getModel(self):
        return self.model
    def getPrice(self):
        return self.price
    def __str__(self):
        return f"My car is a {self.model} {self.car}, priced at {self.price}"
    
car1 = Car("Honda Civic", 2018, "$13,000")
car2 = Car("Toyota Prius", 2023, "$28,000")
car3 = Car("Chevrolet Impala", 2020, "$22,000")
print(car1)
print(car2)
print(car3)

My car is a 2018 Honda Civic, priced at $13,000
My car is a 2023 Toyota Prius, priced at $28,000
My car is a 2020 Chevrolet Impala, priced at $22,000

Homework:

Assignment 1: How do you use functions?

Create a function that takes in an array as the parameter and returns the array of distinct values. DON’T USE SETS. TEST ARRAY: arr1 = [2,1,3,2,0,2,0,0,4,2,0,0,0,2,0,0,1,2,3,0,7,4,5,2,1,2,3,4,6].

arr1 = [2,1,3,2,0,2,0,0,4,2,0,0,0,2,0,0,1,2,3,0,7,4,5,2,1,2,3,4,6]

def onlyUnique(lst):
    new_lst = []
    for element in lst:
        if element not in new_lst:
            new_lst.append(element)
        else:
            continue
    return new_lst

print(onlyUnique(arr1))

[2, 1, 3, 0, 4, 7, 5, 6]

Assignment 2:

Create a student class that...

Has a constructor that takes three parameters as attributes
- email
- name
- grade
Three getter methods to access the name, email, and grade
Three setter methods to modify the name, email, and grade
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}
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 getName(self):
        return self.name
    def getEmail(self):
        return self.email
    def getGrade(self):
        return self.grade
    def setName(self, name):
        self.name = name
    def setEmail(self, email):
        self.email = email
    def setGrade(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}."

advik = Student(name="advik", email="funnykidland@gmail.com", grade=10)

print(advik)

My name is advik. My email is funnykidland@gmail.com. My grade is 10

Old Assignment 1(Extra credit)

# Runs fine in repl.it

import turtle

pen = turtle.Turtle()
# pen is the instance of Turtle which has methods that do certain actions

# Necessary methods:
# .forward(50) - moves the pen forward 50 units
# .right(angle) - turns the pen angle degrees right
# OR
# .left(angle) - turns the pen angle degrees left


def shape(sides):
  total = 500
  side_len = total // sides
  angle = 360 / sides
  for side in range(sides):
    pen.forward(side_len)
    pen.right(angle)


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