Prgramming Languages Introduction

SMALLEST INFORMATION UNIT:
1 NIBBLE = 4 BITS
1 BYTE = 8 BITS
1 KILOBYTE (KB) = 8 KILOBITS = 1,024 BYTES = 2¹⁰ BYTES
1 MEGABYTE (MB) = 8 MEGABITS = 1,048,576 BYTES = 2²⁰ BYTES
1 GIGABYTE (GB) = 8 GIGABITS = 1,073,741,824 BYTES = 2³⁰ BYTES
1 TERABYTE (TB) = 8 TERABITS = 1,099,511,627,776 BYTES = 2⁴⁰ BYTES
1 PETABYTE (PB) = 8 PETABITS = 1,125,899,906,842,624 BYTES = 2⁵⁰ BYTES

Programming Languages Levels:

- Binary (Pure machine level/low level)
- 10 + 10 = 100 (Hectic to work with, very difficult for humans to understand)

- Assembly (MOV, ADD, SUB, COM, INC, CARRY) - ADD 5 R2 - .asm (extension file is assembly source code file)

- HLL (High Level Langauge) - C++, Java, COBOL, PYthon, Javascript, 

- AI - Artifical Intelligence LIke ChatGPT etc


Any PL instruction has two parts (state/data + behaviour/fuctions) - Add two numbers 5 and 4
To store data we make use of variables - State
To perform any operation we define functions - Behaviour

Types of Data Types:
Character
String

Boolean

Short
Integer
Long Long Integer

Double
Float

Date
User Defined Data types: Hybrid of primitive data types: array, linkedlist, class, object

Here's a comprehensive explanation of typing systems in programming languages:

**Strong vs Weak Typing**
- Strong Typing: Type constraints are strictly enforced. No **implicit** type conversion.
  Example (Python): `"123" + 456` raises TypeError
- Weak Typing: Allows implicit type conversion between unrelated types.
  Example (JavaScript): `"123" + 456` returns "123456"

**Static vs Dynamic Typing**
- Static Typing: Variable types are checked at compile time. Types must be declared.
  Example (Java): `String name = "John";`
- Dynamic Typing: Variable types are checked at runtime. Types can change.
  Example (Python): `x = "hello"; x = 42` is valid
  
Strong and Statically Typed PL, are genrally faster than weak and dynamically typed PL.
  
JAVA -> Strong and Statically Typed
Python -> Strong and Dynamically Typed
JS -> Weak and Dyanamically typed

**Language Examples**

Java (Strong & Static):
```java
String text = "123";
int num = text; // Compile error
int num = Integer.parseInt(text); // Correct way
```

Python (Strong & Dynamic):
```python
x = "123"
y = x + 456 # TypeError
y = int(x) + 456 # Valid: 579
```

JavaScript (Weak & Dynamic):
```javascript
let x = "123"
let y = x + 456 // "123456"
let z = x - 456 // -333 (converts string to number)
```

Complied PL vs Interpreted PL
JAVA - Complied
Python (RE) - Interpreted
PYPY (RE) - Compiled