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diff --git a/assignment_0.md b/assignment_0.md new file mode 100644 index 0000000..1e0c28a --- /dev/null +++ b/assignment_0.md @@ -0,0 +1,166 @@ +# Notes from Assignment 0 Videos + +## Tenets of OOP - https://www.freecodecamp.org/news/object-oriented-programming-concepts-21bb035f7260/ + +- Four principles: **encanpsulation**, **abstraction**, **inheritance**, **polymorphism** + +### Encapsulation + +- When an object has private and public states/functions/methods +- Example: A "Cat" class + - The class may have private fields, such as mood, hunger, and energy, and a private function `meow()` + - The class may have three public functions/methods + - `sleep()` will increase the object's energy and hunger + - `play()` will increase the object's mood, decrease its energy, and call the private `meow()` function + - `feed()` will decrease the object's hunger, increase its mood, and call the private `meow()` function + +### Abstraction + +- Concept that objects should only expose high-level mechanisms + - Natural extension of Encapsulation concept +- Concept can be seen in real life, for example, a water cooler + - There is technology going on under the hood, but the end user only sees the lever to pull for water +- Another example: smartphone + - Very complicated under the hood, but at a high level, there is only the home button, volume buttons, and charge input + +### Inheritance + +- Idea to combat the problem that often times, many objects are similar but differ slightly +- Involves creating a parent class and a child class, which is derived from the parent +- Example: We can have a Person class with a name and an email + - Then we can define a Teacher, which has all the fields from the Person class, plus an additional subject field + - We could create child classes from Teacher for Private Teacher and Public Teacher, which inherit the teacher fields with their own fields as well + - We could also define a Student, which has all the fields from the Person class, plus additional class and grades fields + +### Polymorphism + +- Creating a method in a parent that differs slightly between child classes that inherit this method +- Example: There is a Shape parent class that has the method `CalculateArea()` + - The child classes are Triangle, Circle, and Rectangle, so each child class will have its own implementation of the `CalculateArea()` method + +--- + +## C++ Data Types - https://www.softwaretestinghelp.com/data-types-in-cpp/ + +- C++ supports two types of data + - Primitive/Standard data types + - User-defined data types + +### Primitve or Standard Data Types + +|Data Type |C++ Keyword|Value Type | +|--------------|-----------|--------------------------------------| +|Character |char |Character (ASCII values) | +|Integer |int |Numeric whole numbers | +|Floating point|float |Decimal values with single precision | +|Decimal point |double |Double precision floating point values| +|Boolean |bool |True or false | +|void |void |Valueless (no value) | +|Wide character|wchar_t |Character including Unicode strings | + +- Primitves can also be modified in memory length using the following data modifiers: + - signed + - unsigned + - short + - long + +### User-defined Data Types + +- **Typedef** + - Sets an alias for another data type + - Example: + - `typedef int age;` + - The above code creates an alias `age` for the `int` data type + +- **Enumeration** + - Example: + - `enum daysOfWeek {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday};` + - The above code creates a data type `daysOfWeek`. It recognizes all the above keywords (they are really aliases for integer values 0, 1, 2, etc.) + - Boolean is, in theory, an enumeration, since it recognizes the keywords true and false + - C++ example: + +``` +#include <iostream> +using namespace std; + +enum daysOfWeek {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}; + +int main(){ + daysOfWeek today; + today = Thursday; + cout << "This is day " << today << " of the week"; + return 0; +} + +--- + +//output: +This is day 4 of the week +``` + +- **Class** + - Collection of objects + - Example: a Student class: + +``` +class student{ + char *name; + int age; + + public: + void printDetails(){ + cout << "Name: " << name; + cout << "Age: " << age; + } +} +``` + +- **Structure** + - A Structure is like a Class, but does not support methods (it can only have variables as its members) + - A Class is really just a structure that can support both variables and methods + - Example: + +``` +struct employee{ + char name[50]; + float salary; + int empId; +}; +``` + +## What C++ is and Why - https://www.youtube.com/watch?v=tbNe-3FXqFM + +### C++ in two lines + +- Direct map to hardware + - of infrastructure and fundamental data types + - Initially from C + - Future: use novel hardware better (caches, multicores, GPUs, FPGAs, SIMD, ...) + +- Zero-overhead abstraction + - Classes, inheritance, generic programming, ... + - Initially from Simula (where it wasn't zero overhead) + +### What really matters? + +- People +- A programming language is a tool, not an end goal + - "Ordinary people" want great systems, not programming languages +- Software developers want great tools + - not just programming language features + +### The onion principle + +- Management of complexity + - Make simple things simple! +- Layer of abstraction + - The more layers you peel off the more you cry + +### An engineering approach + +- Principled and pragmatic design +- Progress gradually guided by feedback +- There are always many tradeoffs + - Choosing is hard +- Design decisions have consequences + - Determine what kind of applications can be done well |