Why c# codes are converted to IL and why C++ codes are converted to machine code not IL?

C++ code after compilation is converted into Machine code because it is platform dependent. C++ is designed and executes it on its own compiler and which is not to design and execute code written on another language.

C# is a .net language and it is a platform independent language. It needs common environment and common format to execute code. .net supports 44 types of languages.  C# (Microsoft) converts all the language code into common code is called as Microsoft Intermediate Language(MSIL). This is executed and loaded by the CLR at time of running.IL code in all other OS with help of CLR, which will integrate in .Net Framework.