Thread: HELP WITH FUNCTIONS and POINTERS!!!

I have a shell of a program and I am suppose to input the rest of the functions, though I am trying to figure out if I am doing this correctly. I have inputed one of the functions but it doesn't seem to work. Can anyone let me know if it seems like i Am doing it correctly....

Code:

 #include <iostream>
#include <iomanip>

using namespace std;

/* Struct to define a book */
struct BOOK_STRUCT { char title[40], 
                     char author[40], 
                     char isdn[10];
                   };


/*Function Name: check_out_book
Parameters: A book
Purpose: Function checks out a book.  Nothing is returned.  
*/
void check_out_book (BOOK_STRUCT* book)
{
     
     
}


/*Function Name: get_book_by_title
Parameters: A library of books, a title, and the size of the library
Purpose: Function returns a pointer to a book based on the title supplied
by the user.  If the book is not found, a null pointer is returned.
*/
BOOK_STRUCT* get_book_by_title (BOOK_STRUCT library[], char* title, int lib_size)
{
             
      
}


/*Function Name: print_avail_books
Parameters: A library of books and the size of the library
Purpose: Function goes through the library and prints only those books 
which are not checked out.
*/
void print_avail_books (BOOK_STRUCT library[], int lib_size)
{
     int row;
     
     cout<<endl<<endl;
     cout<<setw(20)<< "title"
         <<setw(20)<< "author"
         <<endl;
         
         for(row = 0; row < lib_size; row; ++row)
         {
                 cout<<setw(20) << library[row].title
                     <<setw(20) << author[row].author;
                 }
         
         }
   
int main()
{
    char in_title[81];  // buffer to contain input from user
    BOOK_STRUCT* book;  // a book pointer 
    int choice=0;       // used by the menu
    int NUM_BOOKS = 2;  // number of books in the library
    
    // library data structure
    BOOK_STRUCT library[] = {{"Gods and Generals", "Jeff Shaara", "123", 0},{"Killer Angels",
                                     "Michael Shaara", "143", 0}};
                
    cout << setprecision(2)
         << setiosflags(ios::fixed)
         << setiosflags(ios::showpoint);
    
    // Output message to user           
    cout<<"Welcome to Fraser Library"<<endl;
    
    // Loop until the user selects exit.
    do{
       cout<<"Please select from the following options."<<endl;
       cout<<"1. Search for a book."<<endl;
       cout<<"2. Print available books."<<endl;
       cout<<"3. Checkout a book."<<endl;
       cout<<"4. Exit"<<endl;
       cout<<"  > ";
       cin>>choice;   //read input
       
       if(cin.good() && choice > 0 && choice < 5){  // Make sure choice is correct
         if(choice == 1 || choice == 3){  // selections require title of the book
           cin.ignore();     // need to ignore the character return from the previous cin
           cout<<"Please enter the title of the book."<<endl<<"  > ";
           
           cin.getline(in_title,81);   //read input from user
           
           book = get_book_by_title(library, in_title, NUM_BOOKS);  // get book
           
           if (book == NULL)  // The book is not in the library
                cout<<endl<<in_title<<" not found.  Please try another title"<<endl<<endl;
           else if (book->checked_out == true) // The book is available but checked out
                cout<<endl<<"Sorry, "<<book->title<<" is checked out.  Please try another title"<<endl<<endl;
           else if (choice == 1) // The book is available and it will be checked out
                cout<<endl<<book->title<<" by "<<book->author<<" is available."<<endl<<endl;
           else{  // The book is available
                 cout<<endl<<book->title<<" is available.  I'll check it out for you now."<<endl<<endl;
                 check_out_book(book);
              }
           }
         else if(choice == 2){ // user wants to print the list of books
            print_avail_books(library, NUM_BOOKS); 
         }
         else{  //user selected exit
           cout<<"Thanks for coming!"<<endl;
           return 0;
         }
       }
       else {   //user provided something we can't understand
          cout<<endl<<"Sorry, I don't understand what you selected.  Please try again"<<endl<<endl;
          choice = 1;  // This just makes sure the user gets a chance make another selection
       }
     }
     while(choice < 4);
    
    return 0;
}

You seem to be missing any way to determine whether a book is checked out. Was your book struct given to you? 'Cause I would expect that information to be in that struct.

Good choice of books

Anyway, you're going to have to be more specific about it not working. What is it doing, versus what you're expecting?