'function' : local function definitions are illegal

Code tries to define a function within a function.

Or, there may be an extra brace in your source code before the location of the C2601 error.

The following sample generates C2601:

// C2601.cpp  
int main() {  
   int i = 0;  
  
   void funcname(int j) {   // C2601  
      j++;  
   }  
}