Intro to Python
Intro
This guide is designed as a quick-reference for Python fundamentals.
1. Strings
Strings can be defined with single, double, or triple quotes.
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print("Hello, world!")
print('Hello, world!')
print("""This is a
multiple line string!""")
print("This string is " + "Awesome") # Concatenation
2. Math Operations
Python follows standard mathematical order (PEMDAS).
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print(50 + 50) # Add
print(50 - 50) # Subtract
print(50 * 50) # Multiply
print(50 / 50) # Divide
print(50 ** 2) # Exponents (50 squared)
print(50 % 6) # Modulus (Remainder)
print(50 // 6) # Floor Division (Drops decimals)
3. Variables & Methods
Variables are used to store data. Methods are functions that belong to an object.
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name = "Hanif" # String
age = 18 # Int
gpa = 3.7 # Float
quote = "Cinta itu buta"
print(quote.upper()) # UPPERCASE
print(quote.lower()) # lowercase
print(len(quote)) # Length of string
# Type conversion (Casting)
print("My name is " + name + " and I am " + str(age) + " years old.")
4. Functions
Functions are reusable blocks of code.
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def who_am_i():
name = "Hanif"
print("I am " + name)
who_am_i() # Calling function
def multiply(x, y):
return x * y # Returns value to the caller
print(multiply(7, 7))
5. Boolean & Relational Operators
Used for logic and comparisons.
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bool1 = True
bool2 = (3 * 3 == 9) # True
test_and = (7 > 5) and (5 < 7) # True
test_or = (7 > 5) or (10 < 2) # True
test_not = not True # False
6. Conditional Statements
Control the flow of your program based on conditions.
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def smoking(age, money):
if (age >= 21) and (money >= 5):
return "Yes, go smoking"
elif (age >= 21) and (money < 5):
return "No money"
elif (age < 21):
return "Too young / Haram"
else:
return "No money and young"
print(smoking(21, 5))
7. Lists & Tuples
Lists are ordered and can be changed. Tuples are ordered but cannot be changed.
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# Lists []
movies = ["Inception", "Interstellar", "Batman"]
print(movies[0]) # First item
movies.append("New") # Add item
movies.pop() # Remove last item
# Tuples ()
grades = ("A", "B", "C")
8. Looping
Use loops to repeat tasks.
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# For Loop (Iterating over a list)
vegetables = ["cucumber", "spinach", "cabbage"]
for x in vegetables:
print(x)
# While Loop (Executing while a condition is true)
i = 1
while i < 10:
print(i)
i += 1
9. Advanced Strings & Formatting
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sentence = "This is a sentence."
print(sentence.split()) # ['This', 'is', 'a', 'sentence.']
# F-Strings (The modern way to format)
movie = "Mr Robot"
print(f"My favorite movie is {movie}.")
10. Dictionaries
Key-value pairs, similar to a real-life dictionary.
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drinks = {"sirap": 2, "oren": 3, "kosong": 1}
print(drinks["sirap"]) # Returns 2
11. Sockets (Networking)
Sockets allow you to connect nodes together over a network.
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import socket
HOST = '127.0.0.1'
PORT = 7777
# Create a socket object (IPv4, TCP)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
12. File Handling
How to read from and write to files.
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# Writing to a file (will overwrite existing)
with open("test.txt", "w") as f:
f.write("Hello from 0xhanif!")
# Appending to a file
with open("test.txt", "a") as f:
f.write("\nAdding a new line.")
# Reading a file
with open("test.txt", "r") as f:
print(f.read())
13. Classes & Objects
Object-Oriented Programming (OOP) allows you to create your own data types.
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class Cat:
def __init__(self, name, age):
self.name = name
self.age = age
def meow(self):
print("Meow!")
def display_info(self):
print("Name:", self.name)
print("Age:", self.age)
# Create Object
cat1 = Cat("Oyen", 5)
cat2 = Cat("Puteh", 3)
cat1.meow() # Output: "Meow!"
cat1.display_info() # Output: "Name: Oyen", "Age: 5"
14. Pro-tip
In Python, indentation (spaces) is part of the syntax. If your code is not aligned correctly, it will throw an IndentationError.