How to Read from a List using LINQ

Question

So I know there is a lot of questions asked on this same exact question, and there are a lot of great answers but still I can't seem to fix my own problem with my code. So I will GREATLY appreciate anything anyone has to offer. I really feel like I have tried everything and I just have no idea what the problem may be. I have been working on this forever. I want to Read from the List and write it to the Console. But When I try to write it it is blank.

public class Admin
{
    public void Maine()
    {
        List<Books> myLibraryBooks = new List<Books>();

                Books book1 = new Books();

                Console.Write("Enter Author Name:");
                book1.Author = Console.ReadLine();

                Console.Write("Enter Book Title:");
                book1.Title = Console.ReadLine();

                Console.Write("Enter Book ISBN:");
                book1.ISBN = Console.ReadLine();

                Console.Write("Enter the Publish Date:");
                book1.Publish_Date = Console.ReadLine();

                myLibraryBooks.Add(new Books() { Author = book1.Author.ToUpper(), Title = book1.Title.ToUpper(), ISBN = book1.ISBN, Publish_Date = book1.Publish_Date.ToUpper() });
                Console.WriteLine("Book added Successfully");


                Console.Write("Enter Author's Name:");
                string input_to_find = Console.ReadLine();
                var author = from Authors in myLibraryBooks
                             where Authors.Author == input_to_find
                             select Authors;

                foreach (var book in author)
                {
                    Console.WriteLine(book.Author, book.Title, book.ISBN, book.Publish_Date);
                }


class Books
{
    public string Author { get; set; }
    public string Title { get; set; }
    public string ISBN { get; set; }
    public string Publish_Date { get; set; }
}

Also, why are you adding a new Books to the list, when you just finished creating one? Why not just add the one that you initialized and populated instead? — Bob G, Feb 16 '13 at 01:09
I think `list.Publish_Date` should be `book.Publish_Date` but i doubt that this is your issue. — Tim Schmelter, Feb 16 '13 at 01:13
Are you entering the Author's name in the console in all uppercase? — Ryan Byrne, Feb 16 '13 at 01:15
No I am converting it to all uppercase so that I can search for an individual string inside the whole list. Thanks — Kyson Gardner, Feb 16 '13 at 01:19
@KysonGardner I dont see you converting the console input of the Authors name to search by. When you enter the search term are you doing it all uppercase? As it stands now if you dont you will not get any matches. — Ryan Byrne, Feb 16 '13 at 01:21
You don't need to make them uppercase to be able to compare case-insensitively. Just use `StringComparer.OrdinalIgnoreCase.Equals(Authors.Author,input_to_find)` — Tim Schmelter, Feb 16 '13 at 01:24
Hey, I have fixed the problem and everything is all good thank you guys so much!!!!! — Kyson Gardner, Feb 16 '13 at 01:38

score 1 · Answer 1 · answered Feb 16 '13 at 01:12

1

One error - you misspelled the entry point method:

// Was Maine()
public void Main() 
{

answered Feb 16 '13 at 01:12

Reed Copsey

554,122
78
1,158
1,373

Hey,I had to change that because Main was already in use. So I had to change it so it would work right. – Kyson Gardner Feb 16 '13 at 01:15

score 0 · Answer 2 · answered Feb 16 '13 at 01:12

0

var books = from book in myLibraryBooks
            where book.Author == input_to_find
            select book;

foreach (var book in books)
{
    Console.WriteLine(book.Author, book.Title, book.ISBN, book.Publish_Date);
}

answered Feb 16 '13 at 01:12

Christoffer Lette

14,346
7
50
58

`list.Publish_Date` should be `book.Publish_Date` – Calvin Allen Feb 16 '13 at 01:13
But what's the difference to your own code apart from the variable names? – Tim Schmelter Feb 16 '13 at 01:26
Yes there is, Kyson. And they are discussing some interesting stuff. No need to panic. You are in control. You are free to accept any answer you like. As long as it's not @Reed's. ;-) – Christoffer Lette Feb 16 '13 at 01:48
Haha ;) Yeah. this site rocks. – Kyson Gardner Feb 16 '13 at 02:44

Calvin Allen · Accepted Answer · 2013-02-16T01:31:18.897

public class Admin
{
    public void Maine()
    {
        List<Books> myLibraryBooks = new List<Books>();

        Books book1 = new Books();

        Console.Write("Enter Author Name:");
        book1.Author = Console.ReadLine();

        Console.Write("Enter Book Title:");
        book1.Title = Console.ReadLine();

        Console.Write("Enter Book ISBN:");
        book1.ISBN = Console.ReadLine();

        Console.Write("Enter the Publish Date:");
        book1.Publish_Date = Console.ReadLine();

        myLibraryBooks.Add(book1);
        Console.WriteLine("Book added Successfully");


        Console.Write("Enter Author's Name:");
        string input_to_find = Console.ReadLine();

        var author = from Authors in myLibraryBooks
                     where StringComparer.OrdinalIgnoreCase.Equals(Authors.Author,input_to_find)
                     select Authors;

        foreach (var book in author)
        {
             Console.WriteLine(String.Format("{0} - {1} - {2} - {3}", book.Author, book.Title, book.ISBN, book.Publish_Date));
        }

    }

    class Books
    {
        public string Author { get; set; }
        public string Title { get; set; }
        public string ISBN { get; set; }
        public string Publish_Date { get; set; }
    }
}

@Calvin.Allen: You should not make it lower/uppercase(although `ToUpper` is less error-prone than `ToLower`). Use `StringComparer.OrdinalIgnoreCase.Equals(Authors.Author,input_to_find)`. http://stackoverflow.com/a/234751/284240 — Tim Schmelter, Feb 16 '13 at 01:27
Yeah I think that ToUpper() just kinda looks better and kind of cooler. But I did try the StringComparer and I now have that in my Programming arsenal. Thanks A LOT. — Kyson Gardner, Feb 16 '13 at 01:43

How to Read from a List using LINQ

3 Answers3