Strings know their length in the CLR because they are represented as BSTRs http://blogs.msdn.com/b/ericlippert/archive/2011/07/19/strings-immutability-and-pers

Strings know their length in the CLR because they are represented as BSTRs http://blogs.msdn.com/b/ericlippert/archive/2011/07/19/strings-immutability-and-persistence.aspx http://blogs.msdn.com/b/ericlippert/archive/2011/07/19/strin... This lets them interoperate with OLE Automation.