I added an existing form (and its references) to another project and I am trying to show the new form. There are no coding issues, just a reference error:
The type or namespace 'frmEmail' could not be found (are you missing a
using directive or an assembly reference?)
I cannot figure out what "using" or reference I failed to use when importing the other form. Any ideas?
Here is the code causing the error:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace Notify_Setup
{
public partial class frmNotifications : Form
{
public frmNotifications()
{
InitializeComponent();
pbBlue.MouseEnter += new EventHandler(pbBlue_MouseEnter);
}
private void pbGreen_Click(object sender, EventArgs e)
{
frmEmail frmEmail = new frmEmail();
frmEmail.Show();
this.Hide();
}
}
}
You need to pull the namespace in. For example, if this was how your form currently was in the other project:
namespace Your.Form.Namespace { // this is important
public class YourForm : Form {
// stuff
}
}
Then in the project you're adding it to.. you need to add your assembly as a reference, then import the namespace in like this:
using Your.Form.Namespace; // import the namespace
namespace Other.Project {
public class OtherClass {
YourForm _form; // this is fine now
}
}
The other options is to fully qualify the type. What this means, is to use the entire namespace and type name in the declaration. It would be like this:
namespace Other.Project {
public class OtherClass {
Your.Form.Namespace.YourForm _form; // this is fine too
}
}
I added an existing form (and it's references) to another project and I am trying to show the new form.
It looks like the form you added was frmNotifications, but is creating an instance of frmEmail. Did you also added it?
Related
So I made a .dll which I added to my project everything works, but when I try to use any of the class from my .dll. I have to specificly use namespace.classname instead of being able to just say Classname even when I put at the top of my project
using namespace
using System;
using MyTestClassLibrary;
using System.IO;
using YangHandler;
namespace UsingMyclassdll
{
class Program
{
static void Main(string[] args)
{
YangHandler.YangHandler yangh = YangHandler.YangHandler.Parse("Rawtext");
Console.ReadKey();
}
}
}
At the line of using Yanghandler visual studio says
Using directive is unnecessary
Isn't this what using is exactly used for to use other namespaces?
YangHandler code
using System;
using System.IO;
namespace YangHandler
{
public class YangHandler
{
public string YangAsRawText { get; private set; }
public static YangHandler Parse(string YangAsRawText)
{
YangHandler handlerToReturn = new YangHandler();
handlerToReturn.YangAsRawText = YangAsRawText;
return handlerToReturn;
}
I know that it could be solved by using namespace aliases under the namespace "UsingMyclassdll" like
using YangHandler = YangHandler.YangHandler;
But isn't there a more normal solution?
Check this very interesting piece of documentation from Microsoft: https://learn.microsoft.com/en-us/dotnet/standard/design-guidelines/names-of-namespaces
DO NOT use the same name for a namespace and a type in that namespace.
For example, do not use Debug as a namespace name and then also provide a class named Debug in the same namespace. Several compilers require such types to be fully qualified.
So your work around is basically defining the fully qualified name as the type and namespace are of the same name.
No work around for this. The compiler can't know if you mean the one or the other.
I have a class named MyFillerClass in the file MyFillerClass.cs like so :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace trial
{
public static class MyFillerClass
{
public static List<string> returnCategoryNames()
{
List<string> catNames = new List<string>();
catNames.Add("one");
catNames.Add("two");
catNames.Add("three");
catNames.Add("Others");
return catNames;
}
}
}
now when i want to call it from somewhere else (like a form class) :
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace trial
{
public partial class Form1 : Form
{
static string lastSelectedCategory;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
listBox1.DataSource = returnCategoryNames(); //error : The name 'returnCategoryNames' does not exist in the current context
lastSelectedCategory = listBox1.SelectedValue.ToString();
}
private void listBox1_SelectedValueChanged(object sender, EventArgs e)
{
lastSelectedCategory = listBox1.SelectedValue.ToString();
System.Diagnostics.Debug.Print("### User choosed " + lastSelectedCategory + " category");
}
}
}
the line "listBox1.DataSource = returnCategoryNames();" produce an error as indicated in the code ,to fix it i have to adjust it to "listBox1.DataSource = MyFillerClass.returnCategoryNames();".
the question is : in a long program that can add a lot of typing ,can i adjust the class MyFillerClass in such a way that i can just call the function like so : returnCategoryNames() ?
No, not in C# up to 5.0. You need to prefix the static method name with the class name.
However, in C# 6.0 there will be static using statements available. This new language feature will allow you to access directly static classes methods.
Yo can't do it in C# yet. To do it, you need to do a none static class and none static method.
You can do an extension method.
To call a function from a class you need to have an object created for that class then only you can call the method defined in the class.
In case of static class no need to create any object. you have to direct call the method followed by the class name.
In your case
MyFillerClass.returnCategoryNames();
I'm sure this is something simple that I am just overlooking, but I can't figure it out. I am new to C# and I'm trying to create a calculator application. I have created my form with all of my buttons/textbox on it. Now I'm creating a new class to handle all of my methods and whatnot. My problem is that whenever I'm trying to reference controls on the form in the second class, I get the "does not exist in the current context" error. How can I solve this?
An example:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication2
{
public class Calculator
{
decimal currentValue = Decimal.Parse(displayValue.text);
}
}
displayValue receives the error. Thank you for any help.
The Controls can be called only from the .cs file which is linked with the form controls.
What you can do is create a parameterized constructor of your Calculator class like this:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication2
{
public class Calculator
{
public Calculator(string displayValue)
{
decimal currentValue = Decimal.Parse(displayValue);
}
}
}
Now, you can call this class in the form .cs where you have buttons and textboxes like this:
Calculator calculate = new Calculator(displayValue.Text);
When you create a new Windows Form Application, there's a designer (which you can interact with to add your buttons and textboxes) and the code-behind (a .cs file).
This .cs file is a partial class, meaning it is also defined by the form you are interacting with. (you can see the nitty gritty details in your .Designer.cs file)
Once you name your buttons and textboxes, you can refer to their names in the code in your partial class!
And when you compile this, your button text will change to "Hello World!"
Hope this helps.
You will find this control in partial class of the form. You can take values from it and do your operation
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
string s = textBox1.Text;
}
}
i've a gallery.aspx with code behind (this is not a project, only have two files), i want to use another c# class called CFileInfo at same directory.
i use using CFileInfo; in gallery.cs but it is not work.
CFileInfo oDetailedFileInfo = new CFileInfo(sFileName);
The above code is also not work. The CFileInfo looks like
public class CFileInfo
{
...
}
There is no namespace created.
How can i use CFileInfo.cs in gallery.cs?
Create your class and with name space
namespace FileObjects
{
public class CFileInfo
{
public CFileInfo() { }
//Add your functions here
}
}
Now you call this in gallyer.aspx
**using FileOBjects;**
using System;
using System.Data;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class gallery : Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
CFileInfo oDetailedFileInfo = new CFileInfo(sFileName);
}
}
You need to put your CFileInfo.cs into App_Code directory. I'm pretty sure that VS compiler issues warning about this.
Try the following, C# has a global (or unnamed) namespace - you can use global:: to access your class::
using myCFileInfo = global::CFileInfo;
(I still feel like a complete newbie in MS Visual environments... so please bear with!)
I'm using Microsoft Visual C# 2008 Express Edition.
I have a project and in that project are two different forms. The .cs file for each form starts out:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace MyNameSpace
{
public partial class MyFormName : Form
{
...
(...and the second is "MyFormName2" but no differences besides that)
I want to write a function that I know both forms are going to need to access. I right-clicked on my project, selected "Add", selected "New Item" then selected "Code File" and named my file "Common.cs" and it gave me a completely blank file that's in my project.
How do I set this up...? I thought I should do the following...
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace MyNameSpace
{
}
...but then when I try to add a function like:
public void mytestfunc() {
}
within that namespace I get the following error:
"Expected class, delegate, enum, interface, or struct"
How do I set things up so I can have "mytestfunc" be available to both MyFormName and MyFormName2?
Thanks!
-Adeena
UPDATE:
Understand (now) that everything must be in a class, but then I don't understand how to really use it. Does that mean I have to create an object? This common function happens to just be some math...
so now if I have this:
namespace MyNameSpace
{
public class MyCommonClass
{
public void testFunc()
{
MessageBox.Show("Hee hee!");
return;
}
}
}
...how do I call testFunc from my Form? Must I do the following:
MyCommonClass temp = new MyCommonClass;
temp.testFunc();
or is there another way to call testFunc?
If you do something like:
namespace MyNameSpace
{
public class myclass
{
public myMethod()
{
// Code
}
}
}
You will be able to instantiate and access it. If you change it to:
namespace MyNameSpace
{
public class myclass
{
public static myMethod()
{
// Code
}
}
}
You will be able to call myClass.myMethod without instantiating a new myClass.
The short answer is that everything needs to be inside a class; I'd suggest you sit down with a basic tutorial to help you get to grips with the basics...
Code need to be inside classes.
It would look something like this:
using System;
namespace MyNameSpace
{
public class CommonHelper
{
public string FormatMyData(object obj)
{
//do something
return String.Empty;
}
}
}
If the function you call is not related to the forms, make it static
namespace myns
{
public static class myhelper
{
public static void DoSomething()
{
}
}
}
and call the method using myhelper.DoSomething();
If the function you want to call is somehow form-related, e.g. common functionality across multiple forms, derive a class from Form (does not need a visual form) and make it base class of the visual forms:
namespace myns
{
public class MyFormBase : Form
{
protected void DoSomethingWithTheForm()
{
}
}
}
and in your form's .cs:
namespace myns
{
public partial class MyFormName : MyFormBase
{
}
}