Difference between managed and unmanaged code
Managed code refers to code that is specifically designed to run within the context of a managed runtime execution environment, such as the Common Language Runtime (CLR) in .NET technology.
What is Managed Code ?
When code is executed under the control of a managed runtime, it is encapsulated within a protected environment and cannot be directly accessed or called from outside the runtime environment. This ensures the integrity and security of the managed code. It establishes a cooperative agreement between the code and the runtime, allowing the runtime to provide various services such as garbage collection, runtime type checking, and reference checking.
One of the significant advantages of using managed code is that it helps prevent common programming mistakes that can result in security vulnerabilities and unstable applications. The runtime automatically handles tasks such as type safety checking, memory management, and the disposal of unused objects, relieving developers from manually addressing these concerns. This not only enhances the security and stability of the application but also reduces the burden of repetitive programming tasks.
What is Unmanaged Code ?
Unmanaged code refers to code that is compiled directly into machine code and executed by the operating system without any intermediate runtime or virtual machine. The resulting code runs directly on the host processor, bypassing any additional abstraction layers. Unmanaged code is specifically compiled for a particular architecture and will only run on the intended platform. If you want to execute the same code on a different architecture, you would need to recompile it for that specific platform.
Unmanaged executable files are essentially binary images containing x86 code, which are loaded directly into memory for execution. This approach typically offers faster code execution, but it also presents challenges in terms of error diagnosis and recovery. Memory allocation, type safety, and security considerations need to be handled manually by the programmer, making unmanaged code susceptible to issues such as memory leaks, buffer overruns, and pointer overrides.
Traditional C/C++ compilers generate unmanaged code, and examples of unmanaged code include COM components, ActiveX interfaces, and Win32 API functions. In contrast, managed code refers to code written in high-level programming languages supported by the Microsoft .NET Framework, such as VB.NET, C#, J#, and JScript.NET. Managed code benefits from the services and features provided by the .NET runtime, including automatic memory management, type safety checks, and built-in security mechanisms. It is worth noting that Visual C++ can be compiled as either managed or unmanaged code, allowing for a combination of both approaches within the same application, depending on the specific requirements and design considerations.