C# – Creating an Inputbox in C# using forms

cformswinforms

Hello I'm currently creating an application which has the need to add server IP addresses to it, as there is no InputBox function in C# I'm trying to complete this using forms, but am very new to the language so not 100% as to what I should do.

At the moment I have my main form and a form which will act as my inputbox which wants to hide on load. Then when the user clicks on the add IP Address on the main form I wish to open up the secondary form and return the IP address entered into a text box on the secondary form.

So how would I go about doing this? Or is there any better ways to achieve similar results?

Best Answer

In your main form, add an event handler for the event Click of button Add Ip Address. In the event handler, do something similar as the code below:

private string m_ipAddress;
private void OnAddIPAddressClicked(object sender, EventArgs e)
{
    using(SetIPAddressForm form = new SetIPAddressForm())
    {
        if (form.ShowDialog() == DialogResult.OK)
        {
            //Create a property in SetIPAddressForm to return the input of user.
            m_ipAddress = form.IPAddress;
        }
    }
}

Edit: Add another example to fit with manemawanna comment.

private void btnAddServer_Click(object sender, EventArgs e)
{
    string ipAdd;
    using(Input form = new Input())
    {
        if (form.ShowDialog() == DialogResult.OK)
        {
            //Create a property in SetIPAddressForm to return the input of user.
            ipAdd = form.IPAddress;
        }
    }
}

In your Input form, add a property:

public class Input : Form
{
    public string IPAddress
    {
        get { return txtInput.Text; }
    }

    private void btnInput_Click(object sender, EventArgs e)
    {
        //Do some validation for the text in txtInput to be sure the ip is well-formated.

        if(ip_well_formated)
        {
            this.DialogResult = DialogResult.OK;
            this.Close();
        }
    }
}

Related Solutions

C# – Should ‘using’ directives be inside or outside the namespace

There is actually a (subtle) difference between the two. Imagine you have the following code in File1.cs:

// File1.cs
using System;
namespace Outer.Inner
{
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now imagine that someone adds another file (File2.cs) to the project that looks like this:

// File2.cs
namespace Outer
{
    class Math
    {
    }
}

The compiler searches Outer before looking at those using directives outside the namespace, so it finds Outer.Math instead of System.Math. Unfortunately (or perhaps fortunately?), Outer.Math has no PI member, so File1 is now broken.

This changes if you put the using inside your namespace declaration, as follows:

// File1b.cs
namespace Outer.Inner
{
    using System;
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now the compiler searches System before searching Outer, finds System.Math, and all is well.

Some would argue that Math might be a bad name for a user-defined class, since there's already one in System; the point here is just that there is a difference, and it affects the maintainability of your code.

It's also interesting to note what happens if Foo is in namespace Outer, rather than Outer.Inner. In that case, adding Outer.Math in File2 breaks File1 regardless of where the using goes. This implies that the compiler searches the innermost enclosing namespace before it looks at any using directive.

C# – Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

As per Prerak K's update comment (since deleted):

I guess I have not presented the question properly.

Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.

So only accessing the value so that corresponding data can be fetched from the database.

The solution you want then should look like:

UserContrl1_LOadDataMethod()
{
    string name = "";
    if(textbox1.InvokeRequired)
    {
        textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
    }
    if(name == "MyName")
    {
        // do whatever
    }
}

Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:

UserContrl1_LOadDataMethod()
{
    if(textbox1.text=="MyName") //<<======Now it wont give exception**
    {
        //Load data correspondin to "MyName"
        //Populate a globale variable List<string> which will be
        //bound to grid at some later stage
        if(InvokeRequired)
        {
            // after we've done all the processing, 
            this.Invoke(new MethodInvoker(delegate {
                // load the control with the appropriate data
            }));
            return;
        }
    }
}

Best Answer

Related Solutions

C# – Should ‘using’ directives be inside or outside the namespace

C# – Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

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