Hey Kyle, let's work through this error together! That expected class-name before '{' token message on your class LinkedList: public ListInterface{ line is one of the most common gotchas with C++ inheritance, and it usually means the compiler doesn't recognize what ListInterface is. Here are the most likely fixes to check:

• Missing include for the ListInterface header
  If your LinkedList.h file doesn't include the header where ListInterface is defined, the compiler has no idea what that name refers to. Add this line at the top of LinkedList.h (make sure the filename matches exactly—case matters on most systems):

  #include "ListInterface.h"
  

  Also, don't forget to add header guards to both files to prevent duplicate inclusion issues. For example, in ListInterface.h:

  #ifndef LIST_INTERFACE_H
  #define LIST_INTERFACE_H
  
  // Your ListInterface class definition here
  
  #endif // LIST_INTERFACE_H
  

• Typos or case mismatches in the class name
  C++ is case-sensitive, so double-check that you're spelling ListInterface exactly as it's defined. If the original class is named listinterface or ListInterfaceImpl, even a tiny difference will break the inheritance.

• ListInterface is in an unreferenced namespace
  If ListInterface is declared inside a namespace (like namespace DataStructures), you need to either qualify the name in your inheritance line:

  class LinkedList: public DataStructures::ListInterface{
  

  Or add a using directive at the top of LinkedList.h (though qualified names are better to avoid namespace pollution):

  using namespace DataStructures;
  

• Invalid definition of ListInterface
  If there's a syntax error in the ListInterface header (like a missing semicolon after the class definition, mismatched braces, or invalid pure virtual function declarations), the compiler might fail to recognize it as a valid class. Go back to ListInterface and double-check its syntax for any mistakes.

If none of these work, try cleaning your project's build artifacts (like object files or cached build data) and recompiling from scratch—sometimes stale build files can cause weird, hard-to-track errors.

内容的提问来源于stack exchange，提问作者Kyle Kappes-Sum