ambigous overload of istream operator when default constructor used

When I use the default constructor for my book object I get an error trying to compile.

Code:

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#include <stdlib.h>

#include "book.h"
#include "author.h"

int main(int argc, char *argv[])
{
  map<string,Book> library;
  char c;
  cout << "Press Enter to Add a Book Q to continue.";
  cin.get(c);
  while ((c!='Q') && (c!='q')){
      Book tempBook();
     
      //error here but if I use Book tempBook("Some Book") no error
      //21 C:\Dev-Cpp\Book1\main.cpp  ambiguous overload for `std::istream& >> Book (&)()' operator

      cin >> tempBook;
      library.insert(make_pair(tempBook.get_ISBN(),tempBook));
      cout << "Press Enter to Add a Book Q to continue.";
      cin.ignore();
      cin.get(c);
  }
 
  map<string,Book>::iterator pos;
  for (pos=library.begin();pos !=library.end();++pos){
    cout << "--------------------------------------------\n";
    cout <<pos->second;
  }
 
 
     
  system("PAUSE");       
  return 0;
}

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Code:

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Book tempBook();

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try

Code:

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Book tempBook;

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Thanks that worked another question how can I use a pointer to the book as in:

Code:

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int main(int argc, char *argv[])
{
  map<string,Book> library;
  char c;
  cout << "Press Enter to Add a Book Q to continue.";
  cin.get(c);
  while ((c!='Q') && (c!='q')){
      Book *tempBook=new Book;
      cin >> *tempBook;
      library.insert(make_pair(*tempBook.get_ISBN(),*tempBook));
      delete tempBook;
      cout << "Press Enter to Add a Book Q to continue.";
      cin.ignore();
      cin.get(c);
  }

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This line is wrong:

Code:

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library.insert(make_pair(*tempBook.get_ISBN(),*tempBook));

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It should be:

Code:

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library.insert(make_pair((*tempBook).get_ISBN(),*tempBook));

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You need the (), because I believe the . has a higher precedence than the dereference operator.

OR you can also do:

Code:

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library.insert(make_pair(tempBook->get_ISBN(),*tempBook));

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If I said anything wrong, please someone correct me.