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Brennan's Notes

Table of Contents:

Programming Language

  • Programming is like a recipe

    • Ingredients and instructions – specific
    • Literal arguments -> Exact
    • Bug: Unexpected happened
    • Crash: Something freezes
  • Order of steps is important, programming is sequential

  • Finding errors and preventing crashes are just as important as creating instructions

  • Syntax is rules, semantics is meaning.
  • Each languages have their own strengths and weaknesses.
  • Machine language is what computers read and understand, which is what high-level languages are converted to.
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# include

int main()
{
    std::cout << "Hello, world!";
    return 0;
}

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document.write("Hello, world!");

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print "Hello, world!"

Running Code

  • Python is an interpretive language, which means that it needs to be converted into machine language before it’s able to run.

    • You convert interpretive language into machine language with compile or interpret or a combination of both.
  • Languages such as C, C++, and Objective-C are compiled languages
  • Languages such as PHP and JavaScript are interpreted languages.
  • Java, C# and Pythonare a combination of both.

Integrated Development Environments

  • XCode: Used to develop Apple programming for iOS and MacOS development.
  • Visual Studio Code: Used to develop in a multitude of languages.
    • Has an auto-complete functionality

Why Python?

  • The most popular programming languages are currently: Java, Python, JavaScript, C++ and C#.
  • Python and JS have concise syntax.
    • JS is a web development language.
    • Python is a general usage language which can create web apps, internal company tools, scientific analysis, and games.

Python Example:

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name = input("Hi, what's your name? ")
age = int(input("How old are you? "))

if (age < 13):
    print("You're too young to register", name)
else:
    print("Feel free to join," name)
  • Statements are the building blocks of any program.
    • They are made up of keywords, expressions and operators
    • Operators are symbols that tell the computer to perform an action with some input.
      • Eg. +, -, *, /
      • The digits would be the operands or input
    • Expressions are
    • Keywords are

There are two ways to write error-free programs; only the third one works. –Alan Perlis

Error Categories:

  • Syntax: Language rules broken
  • Runtime: Unable to execute the program
  • Semantic: Unexpected output

Variables and Data-types:

  • A variable is a container for a value
    • Use the assignment operator = to assign a value to a variable.
  • Datatype are categories for different kinds of variables.
    • Eg. a string or integer
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// In Java, the data type is needed for variables.
String = cookie = "Sugar";
System.out.println(cookie);
  • Variable names should only contain letters, numbers, and underscores.
    • No spaces, and do not start names with a number.
    • Case-sensitive and no keywords allowed

Numbers

  • ** is used for exponents
  • // is a floor division (no remainder)
  • % is used for modulation (only remainder)
  • float is a number that contains a decimal

Strings

  • Representing by beginning and ending quotes (single or double)

Whitespace

  • Add blank lines and spaces for the sake of readability
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# Greet the User
print("Hi!")
name = input("What's your name? ") # Asks user their name

print("It's nice to meet you, " name, "!")
answer = input("Are you enjoying the course so far? ")

if answer == "Yes":
    print("That's really good to hear!")
else:
    exit()

Challenge 1 

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# A message for the user
message = "This is going to be very tricky! >;)"
Message = "Very tricky!"
print(message)

result = 2**3
print("2**3 = " result)
result = 5 - 3
#print("5 - 3 =", result)

print("Challenge complete!")
  • Any expression that breaks down to either true or false is considered a conditional or boolean
  • Relational operators:
    • operand1 (operator) operand2 => True/False
  • Equality operator == and != is an inequation operator.

Conditional Code

if {condition}: execute this code <- block of code four spaces (tab) are needed for code blocks else: execute this code

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plant = "Cacti"

if plant == "Cacti":
    print(plant, "don't need a lot of water!")
else:
    print(plant, "love water!")

print("Thanks!")

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if (5 > 6) {
    System.out.println("nope!");
}
else {
    System.out.println("yes!");
}

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if 5 > 6
    puts "nope!"
else
    puts "yes!"
end

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answer = "Pizza"
# Greet the User
print("Hi!")
# Asks user to guess my favorite food.
food = input("What's my favorite food? ")

if answer == food:
    print("Yep! So amazing!")
else:
    print("Yuck! That's not it!")

print("Thanks for playing!")

Functions

  • Functions are blocks of code packaged together with a name
    • eg. print() or input()
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print("This is The Shimmy!")

def shimmy():
    print("Take one step to the right and stomp!")
    print("Take on step to the left and stomp!")
    print("Shake those hips!")

shimmy()

Creating a function:

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def say_hello():
    print("Hello, friends!") # body of function

say_hello()

Parameters and Arguments

My Solution:

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gold_paid = "Gold"
bronze_paid = "Bronze"

amount_paid = input("Would you like the bronze or gold car wash? ")

def goldWash():
    print("Scrub, scrub, scrub! Ultra clean!")

def bronzeWash():
    print("Scrub, scrub! Pretty clean!")

if amount_paid == gold_paid:
    goldWash()
elif amount_paid == bronze_paid:
    bronzeWash()

Lynda Solution:

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# Parameter in ()
def wash_car(amount_paid):
    if (amount_paid == 12):
        print("Scrub, scrub, scrub! Ultra clean!")

    if (amount_paid == 6):
        print("Scrub, scrub! Pretty clean!")

# Argument in ()
wash_car(6)

Returning Values from Functions 

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def withdraw_money(current_balance, amount):
    if (current_balance >+ amount):
        current_balance = current_balance - amount
        return current_balance

balance = withdraw_money(100, 80)

if (balance <= 50):
    print("A deposit is needed!")
else:
    print("Nothing to see here!")

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void hello() {
    System.out.println("Hi friends!");
}


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// Kotlin programming language
fun checkGrade(grade: String) {
    if (grade == "A")
        println("You aced the class!")
}

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puts "Paycheck Calculator"

def calculate_check(hourly_rate)
    hourly_rate * 40
end

puts "You made #{calculate_check(32)} this week!"

Challenge: Favorite Cities 

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def favorite_city(name):
    if name = "Winnipeg"
        print("Winnipeg, MB")
    if name = "Calgary"
        print("Calgary, AB")
    if name = "Victoria"
        print("Victoria, BC")

print("One of my favorite cities is ")

favorite_city("Winnipeg")

Other Solution:

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def favorite_city(name):
    print("One of my favorite cities is, " name)

favorite_city("Calgary")
favorite_city("Winnipeg")
favorite_city("Victoria")
  • A library is a grouping of variables and functions that someone else has written and verified