C＃-从用户输入中搜索子字符串

Question

I wish to add a search function to my application, I've seen many examples however, all of the data is added by the programmer. How would I implement a search function where the parameters/values aren't pre-defined. I'm guessing I'd have to create another instance of a List<> as I'm already using one?

        public Form1()
    {
        InitializeComponent();
    }

    List<Book> books = new List<Book>();


    private void Form1_Load(object sender, EventArgs e)
    {

    }

    //Settng Values
    public void button1_Click(object sender, EventArgs e)
    {

        Book b = new Book();
        b.Title = textBox1.Text;
        b.ISBN = textBox2.Text;
        b.Onloan = trueCheckBox.Checked;
        listView1.Items.Add(b.Title + ", " + b.ISBN + ", " + b.Onloan);
        books.Add(b);
        textBox1.Text = null;
        textBox2.Text = null;

    }

    //Method to check if item is aviable or note - boolean type
    void avaiable()
    {
        if (trueCheckBox.Checked = true)
        {



            bool onloan = true;
        }

        else
        {
            bool onloan = false;
        }
    }


    private void button2_Click(object sender, EventArgs e)
    {
        Remove();
    }

    //Remove item from both the List & Listview
    void Remove()
    {

        try
        {

            listView1.Items.Remove(listView1.SelectedItems[0]);
            books.RemoveAt(listView1.SelectedItems[0].Index);

        }
        catch
        {

        }
    }


    //Display  information within their field when selected an item is selected
    private void listView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (listView1.SelectedItems.Count == 0)
        {
            return;
        }
        else
        {


            textBox1.Text = books[listView1.SelectedItems[0].Index].Title;
            textBox2.Text = books[listView1.SelectedItems[0].Index].ISBN;
            trueCheckBox.Checked = books[listView1.SelectedItems[0].Index].Onloan;
        }
    }


    //Update the values without having to re-add
    private void button3_Click(object sender, EventArgs e)
    {
        if (listView1.SelectedItems.Count == 0)
        {
            return;
        }
        else
        {
            books[listView1.SelectedItems[0].Index].Title = textBox1.Text;
            books[listView1.SelectedItems[0].Index].ISBN = textBox2.Text;
            books[listView1.SelectedItems[0].Index].Onloan = trueCheckBox.Checked;
            listView1.SelectedItems[0].Text = textBox1.Text + ", " + textBox2.Text + ", "+ trueCheckBox.Checked;
        }
    }

    private void searchBox_TextChanged(object sender, EventArgs e)
    {
        //Here's where I am stuck, I've added a textField and labelled it search box
    }
}


//Class - set & get methods
class Book
{

    public string isbn;
    public string title;
    private Boolean onloan;


    public Book()
    {
        this.isbn = isbn;
        this.title = title;
    }

    public string ISBN
    {
        get { return isbn; }
        set { isbn = value; }
    }
    public string Title
    {

        get { return title; }
        set { title = value; }
    }
    public Boolean Onloan
    {
        get { return onloan; }
        set { onloan = value; }
    }

}

}

Thank you.

EDIT-

Essentially, the search function should allow the user to search for a book using just a substring ie "Mars" should return a the book with the title "The Programmer From Mars" < (Just an example). I'm guessing I'd have to use the .Contain method?

Answer 1

Correct, you will need to use the "Contains" method. Note that "Contains" is case sensitive so you would need to cater for that.

So you would have something like:

var textToSearch = searchBox.Text.ToLower();

var foundBooks = books.Where(book => book.Title.ToLower().Contains(textToSearch)).ToList();

Answer 2

Assuming books is the list of books to search from:

List<Book> searchResult = books.Where(b => b.Title.Contains(searchTerm)).ToList();

This would return a list of books where the input string is found in the title. You can do exact matching with b.Title == searchTerm , and similar with the other properties of Book .

The syntax above is LINQ and can be a little confusing at first, but works very well for things like this.

Edit:

To use this, you'll want using System.Linq;

Since your search seems to be on TextChanged , you'd want to put this code in your searchBox_TextChanged() method:

This gets the textbox the user is typing into:

TextBox searchTerm = sender as TextBox;

And this filters your list of books by the current search:

List<Book> searchResult = books.Where(b => b.Title.Contains(searchTerm.Text)).ToList();

Note as in the other answer you may want to do ToLower() (or upper) to make searches case-insensitive.

All that's left to do now is display the filtered result searchResult back to the user.

Answer 3

Managed to do it, this is my code and it works. If anyone wants to use it for future reference here it is.

        private void button4_Click(object sender, EventArgs e)
    {
        listView1.SelectedItems.Clear();

        for (int  i = listView1.Items.Count -1; i >= 0; i--)
        {
            if (listView1.Items[i].ToString().ToLower().Contains(searchBox.Text.ToLower())) {

                listView1.Items[i].Selected = true;

            }
        }