What do you mean by managed and unmanaged code in net?

Answer 1

"Unmanaged code" is a new name for an old concept. Unmanaged code stands for native machine code. Software is typically written in some high-level language such as Pascal, C or C++. These languages are translated into machine code (aka unmanaged code) by the compiler and its companion tools (assembler, linker, librarian, etc). The generated code runs natively on the host processor; that is, the processor directly executes the code generated by the compiler. This approach typically results in fastest code execution, but diagnosing and recovery from errors might be easier in managed code. Managed code is a new name, but the concept also is pretty old. Today, "managed code" typically stands for the system used by Microsoft .NET, but .NET is just one example of a managed code system. The .NET system takes source code in any of the supported languages (which include C, C++, C#, Pascal, and many others), and translates it into code designed for a virtual machine. The real processor cannot execute this code natively, but it can execute a program which then in turn executes the virtual machine's codes. The program that executes the virtual machine code is known as the virtual machine. While potentially slower than native code execution, the virtual machine can manage code (!) better than real machines. For example, the virtual machine can supervise memory allocation, automatically handle disposal of unused memory, and provide many other services that a native (unmanaged) application typically must explicitly provide. If the virtual machine does its job correctly, all applications using this virtual machine are likely to benefit. Virtual machines are also known under other names. In the Java system, the tool is called a JVM, a Java Virtual Machine. In the Microsoft .NET system, the intermediate language is called MSIL (Microsoft intermediate language), which are executed through a Just-in Time MSIL compiler (JIT-compiler). Early implementations of Pascal generated an intermediate code called P-code, executed at runtime through some P-code interpreter. Other forms of managed code exist.

Answer 2

Managed means garbage collector takes care of resources which are not used any more. If you are using unmanaged code you are on your own taking care of disposing resources.