Programming Basics: Statements & Functions: Crash Course Computer Science #12

Name: Programming Basics: Statements & Functions: Crash Course Computer Science #12
Uploaded: 2017-05-17T20:59:23.000Z
Duration: 22 min 57 s

Introduction to Programming Languages

In this section, we will discuss the importance of programming languages and how they abstract away low-level details.

Programming Languages as Abstractions

Programming languages were developed to allow programmers to focus on solving problems with computation rather than dealing with low-level hardware details.

Just like spoken languages, programming languages have statements that are individual complete thoughts.

Syntax refers to the set of rules that govern the structure and composition of statements in a language. Both spoken languages and programming languages have syntax.

Statements and Variables

Statements in programming languages are similar to complete thoughts in spoken languages. They can be used to assign values to variables using assignment statements.

Programs consist of a series of statements that are executed one after another, similar to following a recipe step by step.

Variables can be named anything, but it is best practice to choose meaningful names for better code understanding.

Control Flow Statements: If Statements

This section introduces control flow statements, specifically focusing on if statements.

Conditional Statements: If Statements

If statements allow us to execute certain code blocks based on whether a condition is true or false. They act as forks in the road where different paths are taken depending on the condition's evaluation result.

The syntax for if statements may vary slightly across different programming languages, but the underlying structure remains the same - if (condition) code block.

If statements can also include an else statement which acts as a catch-all if the condition evaluates to false. The code inside the else block is executed when the condition is false.

Control Flow Statements: Loops

This section introduces loops, specifically focusing on while loops.

Conditional Loops: While Loops

While loops allow a piece of code to be repeated as long as a condition is true. The code inside the loop will continue to execute until the condition becomes false.

The syntax for while loops may vary across programming languages, but they generally follow the structure of while (condition) code block.

Conclusion

In this CrashCourse Computer Science episode, we learned about programming languages and how they abstract away low-level details. We explored statements and variables, control flow statements like if statements, and conditional loops using while statements. These fundamental building blocks are essential in almost all programming languages.

Timestamps provided in square brackets indicate the corresponding part of the video for each section.

Understanding the While Loop

In this section, we explore the concept of a while loop and how it works.

The While Loop

A while loop is a condition-controlled loop that repeats a block of code until a specific condition becomes false.

The loop starts by checking the conditional statement. If it evaluates to true, the code inside the loop is executed.

We analyze an example where the variable "relays" is initially set to 1.

Inside the loop, we encounter the line of code "relays equals relays plus 1", which may seem confusing at first.

To understand this assignment statement, we evaluate the right side of the equation first. In this case, "relays plus 1" results in 2 because "relays" currently holds the value 1.

The result (2) is then stored back into the variable "relays", overwriting its previous value.

This process continues until the conditional statement becomes false.

Working with While Loops

In this section, we continue exploring while loops and their functionality.

Iterating with While Loops

We revisit our example with "relays" and observe how while loops iterate based on a condition.

After executing one iteration of the loop, we check if "relays" (currently holding a value of 2) is less than 4. Since it satisfies this condition, we enter another iteration of the loop.

During each iteration, we increment "relays" by 1 and update its value accordingly.

This process continues until "relays" reaches a value greater than or equal to 4. At that point, the condition becomes false, and we exit the loop.

Introduction to For Loops

In this section, we introduce the concept of a for loop as an alternative to while loops.

The For Loop

A for loop is a count-controlled loop that repeats a specific number of times.

Unlike while loops, which rely on a condition, for loops have a predetermined number of iterations.

We provide an example of a for loop that iterates 10 times. The loop uses the variable "i" and starts at 1, incrementing by 1 until it reaches 10.

Each time the loop encounters the "NEXT" statement, it adds one to "i".

When "i" equals 10, indicating that the loop has been executed 10 times, the loop exits.

Using Loops for Exponential Calculations

In this section, we explore how loops can be used to calculate exponents.

Exponent Calculation with Loops

We discuss the need to calculate exponents in our code and how loops can help achieve this.

To demonstrate this concept, we initialize a variable called "bonus" with a value of 1.

Next, we create a for loop that starts at 1 and iterates up to the level number specified.

Inside the loop, we multiply "bonus" by the number of relays and update its value accordingly.

This process allows us to calculate exponents by multiplying a number by itself multiple times within the loop.

Encapsulating Code with Functions

In this section, we learn about functions and their role in encapsulating code.

Introducing Functions

Functions are named pieces of code that can be packaged and reused throughout a program.

They help compartmentalize and hide complexity, making code more organized and easier to understand.

We discuss the benefits of using functions, such as avoiding code duplication and simplifying bug fixes.

Functions can be called from any part of the program by simply using their name.

Creating a Custom Exponent Function

In this section, we create a custom function to calculate exponents.

Creating an Exponent Function

We transform our exponent calculation code into a function for reusability.

The function is named "exponent" and takes two parameters: "Base" and "Exp".

Inside the function, we perform the same calculations as before but with generic variable names.

To return the result of the exponent calculation, we use the "RETURN" statement with the value stored in 'result'.

This allows us to use the "exponent" function anywhere in our program by passing in appropriate values for Base and Exp.

Using Functions for Bonus Calculation

In this section, we utilize functions to calculate score bonuses based on remaining relays.

Calculating Score Bonuses

We demonstrate how functions can be used to calculate score bonuses based on remaining relays at each level.

First, we initialize the bonus variable to 0.

Then, we check if there are any remaining relays using an if-statement. If so, we call our exponent function with relays and level as parameters.

The exponent function calculates relays raised to the power of level and returns the result, which is then saved into bonus.

This bonus calculation code can be wrapped up as a separate function for future use.

Building Complex Functions

In this section, we explore the concept of building complex functions that call other functions.

Building a Complex Function

We introduce the idea of creating complex functions that call other functions.

We present an example function called "levelFinished" that gets executed when a player finishes a level.

The "levelFinished" function requires inputs such as the number of remaining relays, the level number, and the current score.

This function can utilize other functions, like the bonus calculation function, to perform more complex tasks.

When we call a single line of code, like this The Power of Abstraction

This section explains the power of abstraction in programming and how functions enable us to work with complex code more efficiently.

Understanding the Power of Functions

When we call a single line of code, the complexity is hidden, and we only see the result.

Abstraction allows us to hide internal loops and variables, making code easier to understand.

Functions are essential in modern programming as they allow us to break down complex tasks into smaller, manageable pieces.

Modularizing Programs with Functions

Writing software as one long list of statements is not feasible; it would be too long and difficult to comprehend.

Instead, software consists of thousands of smaller functions, each responsible for different features.

Functions should generally be shorter than 100 lines of code. If a function becomes too long, it's an indication that it should be divided into smaller functions.

Benefits of Modularization

Modularizing programs into functions enables individual programmers or teams to work efficiently on larger projects.

Different programmers can work on different functions simultaneously.

When everyone ensures their code works correctly, combining all the functions should result in a working program.

Leveraging Pre-Written Functions (Libraries)

Modern programming languages come with pre-written functions called libraries.

Libraries are created by expert coders, optimized for efficiency, rigorously tested, and made available to everyone.

These libraries save time by providing ready-to-use functionality for common tasks like exponentiation.

Inheritance: A Key Concept in Object-Oriented Programming

This section introduces inheritance as a fundamental concept in object-oriented programming.

Understanding Inheritance

Inheritance allows objects/classes to inherit properties and behaviors from other objects/classes.

It promotes reusability by creating a hierarchy of classes, where child classes inherit characteristics from parent classes.

Child classes can add or modify inherited properties and behaviors.

Benefits of Inheritance

Inheritance reduces code duplication by allowing us to define common attributes and methods in a parent class.

It promotes code organization and maintainability by grouping related objects/classes together.

Inheritance enables polymorphism, where objects of different classes can be treated as instances of a common superclass.

Types of Inheritance

Single inheritance: A child class inherits from a single parent class.

Multiple inheritance: A child class inherits from multiple parent classes.

Multilevel inheritance: A child class inherits from another child class, forming a hierarchical chain.

Exception Handling: Dealing with Errors

This section discusses exception handling as a mechanism for dealing with errors in programming.

Understanding Exceptions

Exceptions are unexpected events that occur during program execution and disrupt the normal flow.

They can be caused by various factors like invalid input, resource unavailability, or logical errors.

Exception Handling Mechanism

Exception handling allows us to catch and handle exceptions gracefully instead of letting them crash the program.

It involves using try-catch blocks to encapsulate potentially error-prone code and provide alternative paths when exceptions occur.

Try-Catch Blocks

The try block contains the code that might throw an exception.

The catch block catches the thrown exception and specifies how to handle it.

Multiple catch blocks can be used to handle different types of exceptions.

Finally Block

The finally block is optional but useful for executing cleanup code regardless of whether an exception occurred or not.

It ensures that certain actions (e.g., closing files or releasing resources) are always performed before exiting the program.