Code is just a series of instructions for a computer to follow one after another. Programs can have a lot of instructions.
Code runs in order, starting at the top of the program.
print() function to print on console.
Each print() instruction prints on a new line.
"Syntax" is jargon for "valid code that the computer can understand".
Syntax: The rules for how expressions and statements should be structured in a language.
An expression produces a value. You can use it wherever a value is needed.
Examples:
Python: 2 + 3, "hi".upper(), len([1,2,3]), x if x>0 else 0
JavaScript: a * b, user?.name, [1,2].map(f)
A statement performs an action. It doesn’t itself produce a value you can use.
Examples:
Python: if, for, while, def, class, return, import, pass
JavaScript: if (...) {}, for (...) {}, function f(){}, return;, let x = 1;
Notes:
Many languages allow “expression statements,” where a standalone expression is used as a statement (e.g., a function call print("hi")).
In Python, assignment like x = 3 is a statement, not an expression. In JavaScript, x = 3 is an expression that can be used inside others.
Expressions can be nested; statements control structure and scope.
Variables are how we store data as our program runs.
Comments don't do... anything. They are ignored by the Python interpreter. That said, they're good for what the name implies: adding comments to your code in plain English.
A single # makes the rest of the line a comment
You can use triple quotes to start and end multi-line comments as well
Variable names can not have spaces, they're continuous strings of characters.
The creator of the Python language himself, Guido van Rossum, implores us to use snake_case for variable names. What is snake case? It's just a style for writing variable names.
Snake Case: All words are lowercase and separated by underscores --> num_new_users --> Python, Ruby, Rust
Camel Case: Capitalize the first letter of each word except the first one --> numNewUsers --> JavaScript, Java
Pascal Case: Capitalize the first letter of each word --> NumNewUsers --> C#, C++