Basic Terms
Before continue writing more lines of code, we need to learn some basic terms. In this handout, I’m going to talk about what are them, not how to using them. We will learn to use them in detail one by one when the course goes on.
Value
A value …. is a value. But in programming, it’s not just a number. A value can be a word, a number, a color….
Variable
Have you ever see something like x=10 in your math class? The “x” here represents 10.
In Python, the concept of a variable is like “x” in your math class, but have little difference.
| Math | Python | |
|---|---|---|
| Name | x,y or other letters | Any name you want (but needs to follow certain naming rules), for example rest, inputValue, player_head_left. |
| Value | numbers | Everything. Numbers, sentences, colors, lists and a lot more. |
| Mutability (can it change) | cannot change | variable is mutable (at least most of the time), you can change it to anything at any time you want. |
Operator
Math class again. The concept of operators are like plus sign, minus sign in math.
Some operators in Math are very similar to math (for example +, -): they all result as a number.
Other operators in Python are not doing math, they are checking is True or False. For example they can check if the value of one variable equals another variable’s value.
Function
You may heard about function in math class. (Hahaha math class yet again) Let’s do a comparison.
| Math | Python | |
|---|---|---|
| input (parameters) | only numbers | anything, same as what you can put in a variable |
| output (return value) | one number | anything, a function can don’t return anything, return one value or return multiple value at once |
| what does function do | mathematic calculation | anything, maybe add two number, maybe draw an image on the screen, maybe take a picture of you |
As you can see, functions in Python can do much more than it in math.
Functions is a type of value too. In other words, a function is stored in a variable and can be assigned to other variables like other types of the value. //move this line to function
Control Flow
Finally, we got something that’s not exist in your math class.
What control flow does is it controls how your code flows. (Okay I know it sounds obvious) You can use Control flow to let a certain part of your code only execute if the condition you gave it is satisfied. Or you can use control flow to run a part of your code multiple times.
Comment
Reading “languages of computers” is sometimes boring and hard to understand. You can write some comments in your code to help yourself and others to understand your code better. When your program is executed, your comment will ignored by computer.
Next: Values
