When comparing Python and C# in the context of writing code (e.g., declaring variables, creating functions, or defining classes), there are several key differences due to their distinct design philosophies, syntax, and paradigms. Python is a dynamically typed, interpreted language with a focus on simplicity and readability, while C# is a statically typed, compiled language designed for robustness and performance, primarily within the .NET ecosystem. Below is a pointwise list of the key differences, followed by a difference table summarizing them.

Key Differences (Pointwise)

1. Typing System:

   • Python: Dynamically typed; variable types are determined at runtime, and no explicit type declaration is required (e.g., x = 5).
   • C#: Statically typed; variables must be explicitly declared with a type (e.g., int x = 5), and type checking occurs at compile time.

2. Syntax for Variable Declaration:

   • Python: No type keywords or semicolons needed (e.g., name = "Alice").
   • C#: Requires type specification and semicolons (e.g., string name = "Alice";). C# also supports var for implicit typing, but the type is still resolved at compile time.

3. Function Declaration:

   • Python: Uses def keyword, no return type or parameter types specified (e.g., def add(a, b): return a + b).
   • C#: Requires explicit return type and parameter types, uses curly braces (e.g., int Add(int a, int b) { return a + b; }).

4. Class Declaration:

   • Python: Uses class keyword, no access modifiers by default, and indentation defines scope (e.g., class Person:). Attributes and methods are defined without explicit types.
   • C#: Uses class keyword with optional access modifiers (e.g., public class Person { }). Members require explicit types and access modifiers (e.g., public string Name;).

5. Access Modifiers:

   • Python: No strict access modifiers; uses naming conventions like _ (protected) or __ (private) for encapsulation, but these are not enforced.
   • C#: Explicit access modifiers like public, private, protected, internal control visibility strictly.

6. Indentation vs. Braces:

   • Python: Uses indentation to define code blocks, enforcing readable formatting.
   • C#: Uses curly braces {} to define code blocks, with indentation being optional (but conventional).

7. Constructor Syntax:

   • Python: Uses __init__ method (e.g., def __init__(self, name): self.name = name).
   • C#: Uses the class name or explicit constructor with access modifiers (e.g., public Person(string name) { Name = name; }).

8. Inheritance:

   • Python: Supports multiple inheritance; base classes are listed in parentheses (e.g., class Child(Parent1, Parent2):).
   • C#: Supports single class inheritance but multiple interface implementation (e.g., class Child : Parent, IInterface { }).

9. Method Overriding:

   • Python: No explicit keywords; methods are overridden by redefining them in the child class.
   • C#: Requires virtual in the base class and override in the derived class for explicit overriding.

10. Exception Handling:

    • Python: Uses try/except/finally (e.g., try: x = 1/0 except ZeroDivisionError: print("Error")).
    • C#: Uses try/catch/finally with typed exceptions (e.g., try { int x = 1/0; } catch (DivideByZeroException) { Console.WriteLine("Error"); }).

11. Properties:

    • Python: Uses @property decorator for getter/setter (e.g., @property def name(self): return self._name).
    • C#: Uses property syntax with get/set (e.g., public string Name { get; set; }).

12. Compilation and Execution:

    • Python: Interpreted, runs directly without compilation, but slower execution.
    • C#: Compiled to Intermediate Language (IL) for .NET, faster execution but requires compilation.

13. Null Handling:

    • Python: Uses None for null values.
    • C#: Uses null, with nullable types (e.g., int?) for value types to support nullability.

14. Type Hints vs. Strict Typing:

    • Python: Supports optional type hints (e.g., def add(a: int, b: int) -> int:), but they are not enforced at runtime.
    • C#: Strict typing enforced at compile time, no optional hints.

15. Platform Dependency:

    • Python: Cross-platform, highly portable with minimal dependencies.
    • C#: Primarily tied to .NET, though .NET Core/.NET 5+ improves cross-platform support.

Difference Table

This table and list capture the primary differences relevant to declaring variables, creating functions, and defining classes, providing a clear comparison for developers transitioning between Python and C#.