Watch this after reading through all the posts
Python Full Course 2024 — freeCodeCamp
Covers lists, for loops with lists, and string concatenation
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Build a simple to-do list program:
todos = []
todos.append("Learn Python")
todos.append("Build a Telegram bot")
todos.append("Deploy my first project")
print("Your To-Do List:")
for index, task in enumerate(todos):
print(f"{index + 1}. {task}")
print(f"Total tasks: {len(todos)}")
Then extend it — ask the user to add their own tasks using input() in a loop
Stop when they type "done"
Then print the full list
Screenshot your output
Bonus — let the user also delete a task by number
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Lists store items by position — index 0, 1, 2...
But sometimes you need to store data by name
Like a real dictionary — look up a word, get its meaning
That is exactly what Python dictionaries do
This lecture covers:
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A dictionary stores data as key-value pairs
Instead of an index number you use a key — a name you choose
user = {
"name": "Ahmed",
"age": 22,
"city": "Dubai",
"is_admin": False
}Accessing values by key:
print(user["name"]) # Ahmed
print(user["age"]) # 22
Safer way using .get() — returns None instead of crashing if key does not exist:
print(user.get("email")) # None
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Adding a new key:
user["email"] = "ahmed@gmail.com"
Updating an existing key:
user["age"] = 23
Deleting a key:
del user["city"]
user.pop("is_admin")
Checking if a key exists:
if "email" in user:
print("Has email")
print(len(user)) # number of keys
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user = {"name": "Ahmed", "age": 22, "city": "Dubai"}
# loop through keys only
for key in user:
print(key)
# loop through values only
for value in user.values():
print(value)
# loop through both — most useful
for key, value in user.items():
print(f"{key}: {value}")Output of last loop:
name: Ahmed
age: 22
city: Dubai
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Dictionaries can contain other dictionaries
This is how real user data is usually structured
users = {
"ahmed": {
"age": 22,
"is_admin": True
},
"sara": {
"age": 19,
"is_admin": False
}
}
print(users["ahmed"]["age"]) # 22
print(users["sara"]["is_admin"]) # FalseYou will see this exact pattern constantly when working with APIs and bots
Telegram sends you user data in this format
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A set is like a list but:
tags = {"python", "bots", "coding", "python"} # duplicate python
print(tags) # {'python', 'bots', 'coding'} — duplicate removedMost common use case — removing duplicates from a list:
numbers = [1, 2, 2, 3, 3, 3, 4]
unique = list(set(numbers))
print(unique) # [1, 2, 3, 4]
Checking membership is also faster with sets than lists
Use sets when you need unique items and do not care about order
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Watch this after reading through all the posts
Python Full Course 2024 — freeCodeCamp
Covers dictionaries, iterating over dictionaries, and associating values
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Build a simple contacts manager using a dictionary:
contacts = {
"Ahmed": "050-1234567",
"Sara": "055-7654321",
"Ali": "052-1112233"
}
# print all contacts
for name, number in contacts.items():
print(f"{name}: {number}")
# search for a contact
search = input("Search name: ").strip().title()
if search in contacts:
print(f"Number: {contacts[search]}")
else:
print("Contact not found")Extend it — let the user add a new contact and delete one
Screenshot your output
Bonus — store each contact as a nested dict with number and email
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You have been writing code that runs top to bottom
But what happens when you need to do the same thing in 10 different places?
You do not copy paste it 10 times
You put it in a function and call it whenever you need it
Functions are one of the most important concepts in programming
Everything in real code is built with functions
This lecture covers:
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You create a function with the def keyword:
def greet():
print("Hello! Welcome to the channel")
Nothing happens yet — you need to call it:
greet() # Hello! Welcome to the channel
greet() # Hello! Welcome to the channel
greet() # Hello! Welcome to the channel
One function, called 3 times
If you need to change the message you change it in one place — not 3
This is the power of functions
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Parameters let you pass data into a function:
def greet(name):
print(f"Hello {name}!")
greet("Ahmed") # Hello Ahmed!
greet("Sara") # Hello Sara!
greet("Ali") # Hello Ali!
Multiple parameters:
def introduce(name, age, city):
print(f"My name is {name}, I am {age} years old and from {city}")
introduce("Ahmed", 22, "Dubai")
Parameter = the variable in the function definition
Argument = the actual value you pass when calling it
People use these words interchangeably — do not stress about it
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Functions can also give something back using return
def add(a, b):
return a + b
result = add(10, 5)
print(result) # 15
Without return your function does something but gives nothing back
With return your function produces a value you can use elsewhere
def is_adult(age):
if age >= 18:
return True
return False
if is_adult(20):
print("Access granted")
else:
print("Access denied")
Return also stops the function immediately
Any code after return does not run
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You can give parameters a default value
If nothing is passed — it uses the default
def greet(name, message="Welcome back"):
print(f"Hello {name}! {message}")
greet("Ahmed") # Hello Ahmed! Welcome back
greet("Sara", "You are now banned") # Hello Sara! You are now banned
Default parameters must always come after non-default ones
You will use this constantly in bot handlers
For example a send_message function where parse_mode defaults to HTML
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Sometimes you do not know how many arguments will be passed
*args — accepts any number of positional arguments as a tuple:
def add_all(*numbers):
return sum(numbers)
print(add_all(1, 2, 3)) # 6
print(add_all(1, 2, 3, 4, 5)) # 15
**kwargs — accepts any number of keyword arguments as a dictionary:
def show_info(**details):
for key, value in details.items():
print(f"{key}: {value}")
show_info(name="Ahmed", age=22, city="Dubai")
You do not need to memorize these right now
Just know they exist — you will see them when reading library code
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