|
|
# [SECTION] Comments in Python
|
|
|
|
|
|
# In Python, comments are written using the "#" symbol.
|
|
|
# Remember that comments are not read by the program; they are only for the user.
|
|
|
# Comments can also be written inline.
|
|
|
|
|
|
# [SECTION] Python Syntax
|
|
|
|
|
|
# print() is a built-in function that displays text or other data in the terminal.
|
|
|
print("Hello world!")
|
|
|
# Result: Hello World!
|
|
|
|
|
|
# Like JavaScript, Python does not require semicolons at the end of statements.
|
|
|
|
|
|
# To run a Python program:
|
|
|
|
|
|
# Windows and Linux
|
|
|
# python discussion.py
|
|
|
|
|
|
# MacOS
|
|
|
# python3 discussion.py
|
|
|
|
|
|
# print("Hello World!")
|
|
|
# Result: IndentationError: unexpected indent
|
|
|
|
|
|
# In many other programming languages, indentation is used only for readability, but in Python, it is essential because it indicates a block of code.
|
|
|
|
|
|
# [SECTION] Naming convention
|
|
|
# The terminology used for variable names is "identifier."
|
|
|
# All identifiers should begin with a letter (A–Z or a–z) or an underscore (_).
|
|
|
# After the first character, identifiers can have any combination of characters.
|
|
|
# Unlike JavaScript, which uses camelCase, Python follows the snake_case convention for variable names, as defined in PEP 8 (Python Enhancement Proposal 8).
|
|
|
# Keywords cannot be used as identifiers.
|
|
|
# Most importantly, identifiers are case-sensitive.
|
|
|
|
|
|
age = 20
|
|
|
middle_initial = "C"
|
|
|
|
|
|
# [SECTION] Data Types
|
|
|
# Data types convey what kind of information a variable holds. There are different types, each with its own purpose.
|
|
|
|
|
|
# In Python, these are the commonly used data types:
|
|
|
|
|
|
# Strings (str) - for alphanumeric characters and symbols
|
|
|
full_name = "John Doe"
|
|
|
secret_code = "Pa$$w0rd"
|
|
|
|
|
|
# Numbers (int, float, complex) - for integers, decimals, and complex numbers
|
|
|
num_of_days = 365
|
|
|
pi_approx = 3.1416
|
|
|
complex_num = 1 + 5j # This is a complex number, j represents the imaginary component
|
|
|
|
|
|
# Boolean (bool) - for truth values
|
|
|
is_learning = True
|
|
|
is_difficult = False
|
|
|
|
|
|
# [SECTION] Using variables
|
|
|
|
|
|
# After declaring variables, they can be used by calling the identifier.
|
|
|
print(full_name)
|
|
|
# Result: John Doe
|
|
|
|
|
|
# Python allows assigning values to multiple variables in a single line:
|
|
|
|
|
|
name1, name2, name3, name4 = "John", "Paul", "George", "Ringo"
|
|
|
print(name1)
|
|
|
# Result: John
|
|
|
print(name2)
|
|
|
# Result: Paul
|
|
|
print(name3)
|
|
|
# Result: George
|
|
|
print(name4)
|
|
|
# Result: Ringo
|
|
|
|
|
|
# In Python, the "+" symbol can be used to concatenate strings.
|
|
|
|
|
|
print("Concatenation in Python:")
|
|
|
|
|
|
print("My name is " + full_name)
|
|
|
# Result: My name is John Doe
|
|
|
|
|
|
# print("My age is " + age)
|
|
|
# Result: TypeError: can only concatenate str (not "int") to str
|
|
|
|
|
|
# [SECTION] Typecasting in Python
|
|
|
|
|
|
# There may be times when you want to specify a type for a variable. This can be done using casting. Here are some functions you can use:
|
|
|
|
|
|
print("Typecasting in Python:")
|
|
|
|
|
|
# str() - converts the value into string
|
|
|
print("My age is " + str(age))
|
|
|
# Result: My age is 20
|
|
|
|
|
|
# float() - converts the value into float
|
|
|
print(float(age))
|
|
|
# Result: 20.0
|
|
|
|
|
|
# int() - converts the value into integer
|
|
|
print(int(pi_approx))
|
|
|
# Result: 3
|
|
|
|
|
|
# Another way to avoid the type error without using typecasting is by using an f-string.
|
|
|
# To use an f-string, add a lowercase f before the string, and place the variable you want to display inside curly braces {}.
|
|
|
print(f"Hi, my name is {full_name}, and I am {age} years old.")
|
|
|
# Result: Hi, my name is John Doe, and I am 20 years old.
|
|
|
|
|
|
# [SECTION] Operations
|
|
|
|
|
|
# Python has families of operators that can be used to manipulate variables.
|
|
|
|
|
|
# Arithmetic operators - performs mathematical operations
|
|
|
print("Arithmetic Operators:")
|
|
|
print(1 + 10)
|
|
|
# Result: 11
|
|
|
print(15 - 8)
|
|
|
# Result: 7
|
|
|
print(18 * 9)
|
|
|
# Result: 162
|
|
|
print(21 / 7)
|
|
|
# Result: 3.0
|
|
|
print(18 % 4)
|
|
|
# Result: 2
|
|
|
print(2 ** 6)
|
|
|
# Result: 64
|
|
|
|
|
|
# Assignment Operators - used to assign or update variable values
|
|
|
print("Assignment Operators:")
|
|
|
num1 = 3
|
|
|
num1 += 4
|
|
|
print(num1)
|
|
|
# Result: 7
|
|
|
|
|
|
# Note: Other assignment operators include -=, *=, /=, %=
|
|
|
|
|
|
# Comparison Operators - used to compare values (returns a boolean value)
|
|
|
print("Comparison Operators:")
|
|
|
print(1 == 1)
|
|
|
# Result: True
|
|
|
|
|
|
# Note: Other comparison operators include !=, >=, <=, >, <
|
|
|
|
|
|
# Logical Operators - used to combine or evaluate multiple conditions
|
|
|
print("Logical Operators:")
|
|
|
print(True and False)
|
|
|
# Result: False
|
|
|
print(not False)
|
|
|
# Result: True
|
|
|
print(False or True)
|
|
|
# Result: True |