Getting Started with Python: Control Structures and Functions

I am studying Python with @skillcrush, in this article we cover control structures and functions

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🐍 Greetings travelers! We are studying Python with Skillcrush. In this article we cover control structures and functions.

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Control Structures

→ CONTROL STRUCTURES

Let your code keep running if a condition is true, and stop running if a condition is false.

Tools to build control structures:

1. Comparison Operators

2. The IF statement control structure

3. The boolean data type

4. The try and except control structure

→ COMPARISON OPERATORS

Symbols you can use to compare two or more values.

→ IF STATEMENTS

Similar to comparison operators in that they return true or false, but they use an “if” keyword instead of math symbols.

→ BOOLEANS

A data type with only two possible values: true or false.

→ BOOLEAN OPERATORS

“and”, “or”, and “not”.

→ TRY AND EXCEPT

A control structure for when a user might input an incorrect or unexpected value.

→ USER INPUT

When someone uses an input device, like a keyboard or mouse, to interact with a program.

Most common comparison operators:

• <  less than: 4 < 5

• >  greater than: 5 > 4

• ==  equal to: 5 == 5

• <=  less than or equal to: 4 <= 4

• >=  greater than or equal to: 4 >= 4

• !=  not equal to: 4 != 5

Boolean operators include the keywords and, or, and not. 

• The and Boolean operator will check if all conditions are true or false. 

• The or Boolean operator tests if just one condition is true. 

• The not Boolean operator checks if one condition is false.

len()

The len function will count the number of characters, or length of a string.

Challenge - Birthday Reminder App

Definitely feeling more confident in what I’m learning with Python thanks to my background now in JavaScript. It makes me feel more comfortable playing around in the code. I went ahead and added in the print() section the person’s name, which is something we haven’t covered yet.

Check out the app here:

Replit

Use names like “Janet”, “Rowan”, or “Winona” to see results. Otherwise you will receive a message letting you know the birthday is not in the system.

Feedback Challenge - Error Handling with Try and Except

In the courses with Skillcrush there are feedback challenges. Meaning we can submit our code to the teachers and they will give us feedback on our work.

I was trying to combined a string with the sum total amount, but I had to create a separate print statement to do so.

Replit

That wraps our Control Structures. On to Functions now!

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Functions

• Writing Functions

• Using different variable types in your functions

→ DEFINING A FUNCTION

Telling the computer what the function is called and what it does.

→DEF

To write a function

→ VARIABLE SCOPE

How accessible a variable is, AKA if it can be used throughout your code or just in a single function.

→ GLOBAL VARIABLE

Can be used in any function in the code, but must be initially defined outside of a function.

→ LOCAL VARIABLE

A variable that is only recognized inside of the function it is defined in.

BUILDING FUNCTIONS

def log_out(username):
   goodbye = "Thanks for visiting," + username + "!" 
   return goodbye

I see some similarities to JavaScript here, but I feel like Functions I’m still trying to grasp in JS as well.

DEF - to define a function

Followed by the function name: log_out

Padding an argument in the parenthesis: (username)

: (colon) is like the semi-colon in JS

Inside the function variables can be written or other types of actions.

return statement is used to end the function.

RUNNING FUNCTIONS

Next we need to run it, in the example given it’s through a print function.

print(log_out("Matthew"))

This combined the log_out message with “Matthew” so it says “Thanks for visiting, Matthew!”

VARIABLE SCOPE

Global Example:

username = "Matthew"
email = "HappyMatthew@gmail.com"
about_me = "I love a good sandwich! PB and J, plz."

Local Example:

def log_in(username):
   welcome = "Hi there," + username + "!"
   reminder = "Don't forget to change your password in the next 10     days.!"

Hours Worked Challenge

I struggled a bit on this one. I didn’t realize in the return that we could calculate the arguments being passed through the function.

Replit

Overtime Pay Challenge

I followed the instructions and it was pretty straight forward. Next thing I would want to do is explain why the 50hours statement earned so much more. Or ideally change this to be an input based calculator and then display a statement if folks work overtime.

Replit

Monthly Income Challenge

I definitely felt tempted to use the solution code at first. Then I told myself to just write it best as I could. To write SOMETHING! Try SOMETHING! And turns out… I actually got it right!

The big thing here is to not be afraid to fail. To write something, even if it’s wrong. Because then I at least tried.

Replit

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I’ve loved beginning to learn Python! Now that I have done work in both JavaScript and PHP I could see how once you learn one language it can be easier to adapt it to others. In the next article about Python we will cover modules and lists.

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What did you think? Leave me a comment and share!

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