error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup

Question

I don't know what's wrong with it.. I can't find where the error is, commenting out the implementation doesn't resolve the error either.

Header File

#ifndef MAIN_SAVITCH_SEQUENCE_H #define MAIN_SAVITCH_SEQUENCE_H #include <cstdlib>  // Provides size_t  namespace main_savitch_3 {     class sequence     {     public:         // TYPEDEFS and MEMBER CONSTANTS         typedef double value_type;         typedef std::size_t size_type;         static const size_type CAPACITY = 30;         // CONSTRUCTOR         sequence( );         // MODIFICATION MEMBER FUNCTIONS         void start( );         void advance( );         void insert(const value_type& entry);         void attach(const value_type& entry);         void remove_current( );         // CONSTANT MEMBER FUNCTIONS         size_type size( ) const;         bool is_item( ) const;         value_type current( ) const;     private:         value_type data[CAPACITY];         size_type used;         size_type current_index;     }; }  #endif 

Source

#include "sequence1.h" #include <assert.h>  namespace main_savitch_3 {      // Default constructer - sequence is empty     sequence::sequence()     {         used = current_index = 0;     }       // Start the iteration     void sequence::start()     {         current_index = 0;     }     // Iterate     void sequence::advance()     {         current_index++;     }       // Number of items in the sequence     sequence::size_type sequence::size() const     {         return used;     }     // Checks if there is a current item     bool sequence::is_item() const     {         return current_index <= used && used > 0;     }     // Returns the current value     sequence::value_type sequence::current() const     {         assert(is_item()); // no current item         return data[current_index];     }       // Adds an item BEFORE the current index     void sequence::insert(const value_type& entry)     {         assert(entry != 0); // pointer is invalid         assert(current_index < sequence::CAPACITY); // no room to add an item          // move items up - starting with the last item and working down to the current item         // arrays start at 0, so the -1 adjusts it         for (size_type i = used - 1; i >= current_index; i--)             data[i + 1] = data[i];          data[current_index] = entry;     }     // Adds an item AFTER the current index     void sequence::attach(const value_type& entry)     {         assert(entry != 0); // pointer is invalid         assert(current_index < sequence::CAPACITY); // no room to add an item          // move items up - starting with the last item and working down to the current item         // arrays start at 0, so the -1 adjusts it         for (size_type i = used - 1; i > current_index; i--)             data[i + 1] = data[i];          if (current_index = 0)             data[used] = entry;         else             data[current_index + 1] = entry;     }     // Removes the current item     void sequence::remove_current()     {         for (size_type i = current_index; i < used; i++)             data[i] = data[i + 1];     }  } 

Answer 1

Even if your project has a main() method, the linker sometimes gets confused. You can solve this issue in Visual Studio 2010 by going to

Project -> Properties -> Configuration Properties -> Linker -> System

and changing SubSystem to Console.