Managed vs. Unmanaged Code & .NET Assemblies

Managed vs. Unmanaged Code

Managed Code:
- Code that runs under the supervision of the Common Language Runtime (CLR) in the .NET framework.
- CLR handles memory management, garbage collection, exception handling, and security.
- Examples: C# and VB.NET programs.
Unmanaged Code:
- Code that runs outside the CLR and interacts directly with the operating system.
- The developer is responsible for memory allocation and deallocation.
- Examples: C, C++, and assembly language programs.

Feature	Managed Code	Unmanaged Code
Memory Management	Handled by CLR (Garbage Collection)	Developer must manage manually
Security	Built-in security checks	More vulnerable to memory leaks and attacks
Execution	Runs within .NET environment	Runs directly on OS
Language Examples	C#, VB.NET	C, C++, Assembly

Memory Allocation
- The CLR assigns memory to objects when they are created.
Garbage Collection (GC)
- The GC automatically reclaims memory from objects that are no longer in use, preventing memory leaks.
Just-In-Time (JIT) Compilation
- Converts Intermediate Language (IL) into machine code at runtime.
Exception Handling
- CLR ensures structured exception handling and prevents application crashes.
Security and Type Safety
- Managed code runs in a restricted execution environment, preventing unauthorized access.

Managed Code Example (C#)

using System;
class Program {
    static void Main() {
        Console.WriteLine("Hello, Managed Code!");
    }
}

Unmanaged Code Example (C++)

#include <iostream>
using namespace std;
int main() {
    cout << "Hello, Unmanaged Code!";
    return 0;
}

Interop Between Managed and Unmanaged Code
- Managed code can call unmanaged code using Platform Invocation (P/Invoke).
- Example: Using DllImport to call a Windows API function from C#.