Python Data Types

Data Types

• Numeric Types:
  • Int: whole numbers, e.g., 1, 2, 3
  • Float: decimal numbers, e.g., 3.14, -0.5
  • Complex: complex numbers, e.g., 3+4j, 4-2j
• Sequence Types:
  • String: sequence of characters, e.g., "hello", 'hello'
  • List: ordered collection of items, e.g., [1, 2, 3], ["a", "b", "c"]
  • Tuple: ordered, immutable collection of items, e.g., (1, 2, 3), ("a", "b", "c")
• Mapping Type:
  • Dictionary: unordered collection of key-value pairs, e.g., {"name": "John", "age": 30}
• Set Types:
  • Set: unordered collection of unique items, e.g., {1, 2, 3}, {"a", "b", "c"}
  • Frozenset: unordered, immutable collection of unique items, e.g., frozenset([1, 2, 3])

Control Structures

• Conditional Statements:
  • If: executes a block of code if a condition is true
  • Elif: executes a block of code if a condition is true (used with if)
  • Else: executes a block of code if all conditions are false
• Loops:
  • For: executes a block of code for each item in an iterable
  • While: executes a block of code while a condition is true
• Jump Statements:
  • Break: exits a loop or switch statement
  • Continue: skips the current iteration of a loop
  • Pass: does nothing, used as a placeholder
  • Return: exits a function and returns a value

Object-oriented Programming

• Classes:
  • Define a blueprint for creating objects
  • Can have attributes (data) and methods (functions)
• Objects:
  • Instances of classes
  • Have their own attributes and methods
• Inheritance:
  • A child class can inherit attributes and methods from a parent class
  • Can also override or extend parent class attributes and methods
• Polymorphism:
  • Objects of different classes can be treated as objects of a common superclass
  • Methods can be overridden or overloaded to provide different behavior

File Input/Output

• Reading Files:
  • open() function: opens a file and returns a file object
  • read() method: reads the contents of a file
  • readline() method: reads a single line from a file
  • readlines() method: reads all lines from a file
• Writing Files:
  • open() function: opens a file and returns a file object
  • write() method: writes to a file
  • writelines() method: writes a list of strings to a file
• Modes:
  • r mode: read-only mode
  • w mode: write-only mode (truncates the file if it exists)
  • a mode: append-only mode
  • r+ mode: read and write mode
  • b mode: binary mode (for reading and writing binary files)

Data Types

• Numeric Types:
  • Integers are whole numbers, e.g., 1, 2, 3.
  • Floats are decimal numbers, e.g., 3.14, -0.5.
  • Complex numbers are represented as a + bj, where a and b are floats and j is the imaginary unit, e.g., 3+4j, 4-2j.
• Sequence Types:
  • Strings are sequences of characters, e.g., "hello", 'hello'.
  • Lists are ordered collections of items, e.g., [1, 2, 3], ["a", "b", "c"].
  • Tuples are ordered, immutable collections of items, e.g., (1, 2, 3), ("a", "b", "c").
• Mapping Type:
  • Dictionaries are unordered collections of key-value pairs, e.g., {"name": "John", "age": 30}.
• Set Types:
  • Sets are unordered collections of unique items, e.g., {1, 2, 3}, {"a", "b", "c"}.
  • Frozensets are unordered, immutable collections of unique items, e.g., frozenset([1, 2, 3]).

Control Structures

• Conditional Statements:
  • If statements execute a block of code if a condition is true.
  • Elif statements execute a block of code if a condition is true, used with if statements.
  • Else statements execute a block of code if all conditions are false.
• Loops:
  • For loops execute a block of code for each item in an iterable.
  • While loops execute a block of code while a condition is true.
• Jump Statements:
  • Break statements exit a loop or switch statement.
  • Continue statements skip the current iteration of a loop.
  • Pass statements do nothing, used as a placeholder.
  • Return statements exit a function and return a value.

Object-oriented Programming

• Classes:
  • Classes define a blueprint for creating objects.
  • Classes can have attributes (data) and methods (functions).
• Objects:
  • Objects are instances of classes.
  • Objects have their own attributes and methods.
• Inheritance:
  • Child classes can inherit attributes and methods from parent classes.
  • Child classes can also override or extend parent class attributes and methods.
• Polymorphism:
  • Objects of different classes can be treated as objects of a common superclass.
  • Methods can be overridden or overloaded to provide different behavior.

File Input/Output

• Reading Files:
  • The open() function opens a file and returns a file object.
  • The read() method reads the contents of a file.
  • The readline() method reads a single line from a file.
  • The readlines() method reads all lines from a file.
• Writing Files:
  • The open() function opens a file and returns a file object.
  • The write() method writes to a file.
  • The writelines() method writes a list of strings to a file.
• Modes:
  • The r mode is read-only mode.
  • The w mode is write-only mode, truncating the file if it exists.
  • The a mode is append-only mode.
  • The r+ mode is read and write mode.
  • The b mode is binary mode for reading and writing binary files.

Learn about the different data types in Python, including numeric, sequence, and mapping types. Understand the characteristics of each type and how to work with them in Python programming.