Skip to main content

Featured Post

How to use Tabs in ASP.NET CORE

I want to show Components in a tabs , so first of all create few components. In this project we have three components, First View Component  public class AllViewComponent : ViewComponent     {         private readonly UserManager<ApplicationUser> _userManager;         public AllViewComponent(UserManager<ApplicationUser> userManager)         {             _userManager = userManager;         }         public async Task<IViewComponentResult> InvokeAsync()         {             List<StudentViewModel> allUsers = new List<StudentViewModel>();             var items = await _userManager.Users.ToListAsync();             foreach (var item in items)             {                 allUsers.Add(new StudentViewModel {Id=item.Id, EnrollmentNo = item.EnrollmentNo, FatherName = item.FatherName, Name = item.Name, Age = item.Age, Birthdate = item.Birthdate, Address = item.Address, Gender = item.Gender, Email = item.Email });             }            

Find a control in windows forms

When we drag-n-drop controls in our designer file then we can easily access those controls in our code file directly by its name. But when we dynamically add some controls either in constructor or in load event of form then we can't access them directly in our code.

Let's have an example

  • Add a textbox and a button using drag-n-drop operation on our form i.e. Form1.
  • Leave the name of controls i.e. textBox1 and button1 as they are.
  • Now in constructor add a new textbox dynamically having name "txtBox" with some properties like:

    TextBox txtBox = new TextBox();
    txtBox.Name = "txtBox";
    txtBox.Text = "dynamically added control";
    txtBox.Width = 250;
    txtBox.Location = new Point(10, 10);

    this.Controls.Add(txtBox);
In above code the Name property will be used to find this control. All the remaining properties are familiar to you as in our designer file. At the last we have added this textbox to the form, here the keyword this is pointing Form1.
This form will look like the following screenshot: 

find control in windows form


In click event of button when we will try to access above controls then we notice that "textBox1" will be accessed by its name and "txtBox" will not accessed here.

To access these dynamically added controls we have to use a pre-defined method Find(). This method searches the controls by their name and builds an array as in below code.

Control[] controls = this.Controls.Find("txtBox", false);
foreach (var item in controls)
{
     TextBox txtBox = item as TextBox;
     if (txtBox != null)
        MessageBox.Show("control accessed");
}

In above set of code "controls" will hold the array of all the controls having name "txtBox". One by one we will access items of array and check the type of item. If type of item is TextBox then we found our textbox having name "txtBox".

As we know about naming standards of programming that two controls of the same name cannot exists. Keep in mind the above line, and we are sure that, there will only one control named “txtBox” of type TextBox.

Now we will access the above textbox in one line of code i.e.

TextBox txtBox1 = this.Controls.Find("txtBox", false).First() as TextBox;
if (txtBox1 != null)
 MessageBox.Show("control accessed");

When we run our project and click on button then our form look like this.
find control


Comments

Popular Post

Polynomial representation using Linked List for Data Structure in 'C'

Polynomial representation using Linked List The linked list can be used to represent a polynomial of any degree. Simply the information field is changed according to the number of variables used in the polynomial. If a single variable is used in the polynomial the information field of the node contains two parts: one for coefficient of variable and the other for degree of variable. Let us consider an example to represent a polynomial using linked list as follows: Polynomial:      3x 3 -4x 2 +2x-9 Linked List: In the above linked list, the external pointer ‘ROOT’ point to the first node of the linked list. The first node of the linked list contains the information about the variable with the highest degree. The first node points to the next node with next lowest degree of the variable. Representation of a polynomial using the linked list is beneficial when the operations on the polynomial like addition and subtractions are performed. The resulting polynomial can also

How to use Tabs in ASP.NET CORE

I want to show Components in a tabs , so first of all create few components. In this project we have three components, First View Component  public class AllViewComponent : ViewComponent     {         private readonly UserManager<ApplicationUser> _userManager;         public AllViewComponent(UserManager<ApplicationUser> userManager)         {             _userManager = userManager;         }         public async Task<IViewComponentResult> InvokeAsync()         {             List<StudentViewModel> allUsers = new List<StudentViewModel>();             var items = await _userManager.Users.ToListAsync();             foreach (var item in items)             {                 allUsers.Add(new StudentViewModel {Id=item.Id, EnrollmentNo = item.EnrollmentNo, FatherName = item.FatherName, Name = item.Name, Age = item.Age, Birthdate = item.Birthdate, Address = item.Address, Gender = item.Gender, Email = item.Email });             }            

Memory representation of Linked List Data Structures in C Language

                                 Memory representation of Linked List              In memory the linked list is stored in scattered cells (locations).The memory for each node is allocated dynamically means as and when required. So the Linked List can increase as per the user wish and the size is not fixed, it can vary.                Suppose first node of linked list is allocated with an address 1008. Its graphical representation looks like the figure shown below:       Suppose next node is allocated at an address 506, so the list becomes,   Suppose next node is allocated with an address with an address 10,s the list become, The other way to represent the linked list is as shown below:  In the above representation the data stored in the linked list is “INDIA”, the information part of each node contains one character. The external pointer root points to first node’s address 1005. The link part of the node containing information I contains 1007, the address of