- 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
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
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
Homework:
Assignment 1: How do you use functions?
Create a turtle python function that...
- Takes a single parameter as the number of sides
- Outputs a shape corresponding to the number of sides
- Call the function with the argument being a variable with the user input
Hint:
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):
#code here
numsides = input('How many sides do yoUUUU wnat in YOUUUURRRR shape?!?!!?!: ')
shape(int(numsides))
Assignment 2:
Create a student class that...
- Has a constructor that takes three parameters as attributes
-
- 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