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Struct problem??

acevans2 (27)
Ok guys, this is the last time you'll see me around here. Final assignment to be turned in.

I have all my program written out and I expect it to work, except I get this compile error:

"no matching function for call to 'Book::Book.... "
etc.

I don't understand what the deal is. Does anybody recognize this?

Here is my program. Hopefully it's broken up pretty basically enough that you can skip to the important parts fairly easy.

I am very grateful to anyone who takes the time to look at my issue.


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#include<iostream>
#include<cmath>
#include<iomanip>
#include<fstream>
#include<string.h>

using namespace std;

struct Book
  {
  char newTitle[31];
  char newAuthor[31];
   int newCopies;
   double newPrice;
  };
  
/***************************************************************
Function: print
Use: prints the book attributes

Arguments: A string

Returns: N/A
***************************************************************/ 

void print(Book newBook)
{

cout << "Title: " << newBook.newTitle << endl << "Author: " << newBook.newAuthor << endl << 
	 "Copies in Stock: " << newBook.newCopies << endl << "Price: $" << newBook.newPrice << endl;
	 
} 

/***************************************************************
Function: setTitle
Use: changes the title for the book data

Arguments: a character array

Returns: N/A
***************************************************************/ 

void setTitle(char newTitle[], Book newBook)
{

strcpy(newBook.newTitle, newTitle);

}

/***************************************************************
Function: setAuthor
Use: changes the author for the book data

Arguments: a character array

Returns: N/A
***************************************************************/

void setAuthor(char newAuthor[], Book newBook)
{

strcpy(newBook.newAuthor, newAuthor);

}



/***************************************************************
Function: setCopies
Use: changes the number of copies in stock for the book data

Arguments: an integer representing the number of copies

Returns: N/A
***************************************************************/

void setCopies(int newCopies, Book newBook)
{

if(newCopies >= 0)
{
newBook.newCopies = newCopies;
}
else
{
newBook.newCopies = 0;

cout << endl << "Error: Copies less than zero";
}

}




/***************************************************************
Function: setPrice
Use: changes the price for the book data

Arguments: an integer representing the price

Returns: N/A
***************************************************************/

void setPrice(double newPrice, Book newBook)
{

if(newPrice >= 0)
{
newBook.newPrice = newPrice;
}
else
{
newBook.newPrice = 0;

cout << endl << "Error: Price less than zero";
}

}


/***************************************************************
Function: placeOrder
Use: Determines the outcome of an order placed for a book, whether
it be an insufficient stock, invalid order, or total for a proper
order placed

Arguments: an integer representing the quantity being ordered

Returns: N/A
***************************************************************/


void placeOrder(int orderQuantity, Book newBook)
{

int total;

total = orderQuantity * (newBook.newPrice);


if (orderQuantity <= 0)
{
cout << endl << "Invalid Order Quantity";
}
else if (orderQuantity > newBook.newCopies)
{
cout << endl << "Insufficient Stock";
}
else 
{
newBook.newCopies -= orderQuantity;

cout << endl << "Total Cost: " << total;
}

}


/***************************************************************
Function: addStock
Use: Determines the outcome of a restocking procedure taking place

Arguments: an integer representing the quantity being restocked

Returns: N/A
***************************************************************/

void addStock(int restockQuantity, Book newBook)
{

if (restockQuantity <= 0)
cout << endl << "Invalid quantity";
else
newBook.newCopies += restockQuantity;

}

/***************************************************************
Function: main
Use: runs everything else

Arguments:N/A

Returns: N/A
***************************************************************/

int main()
{

Book newBook("Soylent Green", "Andrew Evans", 31, 20);

Book fakeBook("Errors", "Rules Broken", -2, -3);

cout << endl << "Book Information" << endl;
print(newBook);
cout << endl << "Changing Book Title" << endl;
setTitle("This is a New Title", newBook);
cout << endl << "New Book Information" << endl;
print(newBook);
cout << endl << "Changing Book Author" << endl;
setAuthor("Bob Barker", newBook);
cout << endl << "New Book Information" << endl;
print(newBook);
cout << endl << "Changing Copies of Book" << endl;
setCopies(-5, newBook);
cout << endl << "New Book Information" << endl;
print(newBook);
cout << endl << "Changing Copies of Book" << endl;
setCopies(20, newBook);
cout << endl << "New Book Information" << endl;
print(newBook);
cout << endl << "Changing Book Price" << endl;
setPrice(-4, newBook);
cout << endl << "New Book Information" << endl;
print(newBook);
cout << endl << "Changing Book Price" << endl;
setPrice(25, newBook);
cout << endl << "New Book Information" << endl;
print(newBook);
cout << endl << "Placing Order" << endl;
placeOrder(99, newBook);
cout << endl << "Placing Order" << endl;
placeOrder(3, newBook);
cout << endl << "New Book Information" << endl;
print(newBook);
cout << endl << "Adding Stock" << endl;
addStock(0, newBook);
cout << endl << "Adding Stock" << endl;
addStock(12, newBook);
cout << endl << "New Book Information" << endl;
print(newBook);


return 0;

}
mahlerfive (119)
Since Book is a struct, you cannot create a new book the way you are. You are trying to call a Book constructor method which doesn't exist. Instead you should make Book a class, define a constructor method, and make all the other book related functions methods of the Book class.
jsmith (5804)
structs may also have constructors, destructors, and methods.

acevans2 (27)
I don't quite understand what you mean by making it a class... how do you define it that way?

Thanks for the help guys!
jsmith (5804)
Just change the keyword struct to class, then add public: as the first line inside it.
Although as I said above, there is no need to do this.
Poke386 (109)
You need to define a constructor for your struct.

Or you can just:
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Book newbook;
strcpy(newbook.newTitle,"Soylent Green");
strcpy(newbook.newAuthor,"Andrew Evans");
newbook.newCopies=31;
newbook.newPrice=20.0;

For obvious reasons a constructor is more convenient.
acevans2 (27)
Thanks guys, but I just re-read the assignment and I have to have it as a 'class' anyway- I can't use the struct alternative methods.

So jsmith: I have it turned into a class with public datatypes. I still have that same error message that I started off with though.

How do I define newBook now that I have the class like so: 

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class Book
  {
  public:
  char newTitle[31];
  char newAuthor[31];
 
  int newCopies;
  
  double newPrice;
  
  
  Book(char *, char *, int, double);
  
  };


Once again, thank you a ton guys.

EDIT:

I'm calling it like this:
Book newBook("The Fabulous Life of Mr. Burns", "Andrew Evans", 31, 20.0);

And the error message is "undefined reference to Book::Book.... "

Last edited on
helios (17574)
It's not enough with just declaring the constructor. You also need to implement it either inside the class/struct/whatever or outside.
Last edited on
acevans2 (27)
I'm just kinda learning about 'class' definitions now, so I probably look silly...

I have it defined as follows now:
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class Book
{
  public:
  char newTitle[31];
  char newAuthor[31];
  int newCopies;
  double newPrice;
  
  
  public:
  Book(char newTitle[], char newAuthor[], int newCopies, double newPrice)
  {
   
    strcpy(this.newTitle, newTitle);
	strcpy(this.newAuthor, newAuthor);
	this.newCopies = newCopies;
	this.newPrice = newPrice;
  }

};
  
  
public class newBook
{

  public static void Main()
  {

    // create a Book object using the constructor
    // defined in the class
    Book newBook = new Book("The Fabulous Life of Mr. Burns", "Andrew Evans", 14, 20.20);

    

  }

}


But I get errors for the 'this' lines

"... is of non-class type 'Book* const' ".

How am I supposed to do those properly? I had it as 'newBook.??' before but newBook isn't defined until later. Some google search showed me the same kind of declaration using 'this', but it isn't working.

There's also a random "expected unqualified-id before "public" appearing in line 23 there :S
Last edited on
Bazzy (6281)
This is a pointer so use this->/*member*/, not this./*member*/

PS: If you are using only public members, the struct allows you less typing but it is the same as a class ( http://www.cplusplus.com/forum/beginner/5980/ )
Last edited on
helios (17574)
Wait... That's C#!
Last edited on
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