We Keep Coding

Run method from different scope

I know that what i need help with is not called the Parent but that was the closest word i could think of to describe this situation.
This is not actual code i'm using.
I have MainClass which contains object ObjectA.
class MainClass
{
public int mode = 0;
ObjectA obj = new ObjectA();
}
I need to access the mode variable from the ObjectA object. Is this possible? I feel like if i could at least call a method in MainClass from obj i would be all set. Also I'm aware calling MainClass a parent in this sense is incorrect, what is the correct term for both the MainClass and obj in this.

Assuming you are able to change MainClass, I can think of two options:
Add a reference to MainClass when you create an ObjectA instance.
Like you said in your comments, use events.
Using a reference:
class MainClass
{
public int mode = 31416;
ObjectA obj;
public MainClass()
{
obj = new ObjectA(this);
}
public int GetMainClassMode()
{
return mode;
}
public void Test() {
Console.WriteLine("Calling test method inside obj");
obj.Test();
}
}
class ObjectA {
MainClass parent = null;
public ObjectA(MainClass parent)
{
this.parent = parent;
}
public void Test()
{
if (parent != null)
{
Console.WriteLine("Getting mode from 'parent' MainClass");
Console.WriteLine(string.Format("Mode = {0}", parent.GetMainClassMode()));
}
}
}
Using events:
class MainClass
{
public int mode = 31416;
ObjectA obj = new ObjectA();
public MainClass()
{
obj.ValueReturnEvent += HandleValueReturnEvent;
}
public int GetMainClassMode()
{
return mode;
}
// Handle event, return data
private int HandleValueReturnEvent(object sender, EventArgs e)
{
return mode;
}
public void Test() {
Console.WriteLine("Calling test method inside obj");
obj.Test();
}
}
class ObjectA {
// delegate
public delegate int ReturnValueEventHandler(object sender, EventArgs args);
// event
public event ReturnValueEventHandler ValueReturnEvent;
public void Test()
{
// make sure at least one subscriber
if (ValueReturnEvent != null)
{
// note the event is returning a value
var myValue = ValueReturnEvent(this, null);
Console.WriteLine("Getting mode from 'parent' MainClass");
Console.WriteLine(string.Format("Mode = {0}", myValue));
}
}
}
On both cases, you get this output:
Calling test method inside obj
Getting mode from 'parent' MainClass
Mode = 31416

Even though you've got your answer, you could also simply inject it into your ObjectA ... have a constructor that takes an int, and when you create the object pass the mode in and save it in that object.
I find it cleaner that the object uses whatever it needs from its scope, rather than accessing the parent to ask for a variable.
I'm not saying it might not be needed, it just another thought.

You'll have to wire things up to let the child know about the parent for this to work. Something like this:
class ParentClass
{
public int mode = 0;
public ChildClass child = null;
public ParentClass()
{
child = new ChildClass(this);
}
}
class ChildClass
{
public readonly ParentClass parent = null;
public ChildClass (ParentClass parent)
{
this.parent = parent;
}
public int MethodThatReadsParentMode()
{
int mode = parent.mode;
return mode;
}
}

You make field mode public, so I assume it's possible that someone who uses class MainClass do can change this field.
Let's assume program looks like this.
class Program {
var main = new MainClass();
main.mode = 1;
}
Your obj field is private, so Program cannot access it.
So, when someone changed field mode, ObjectA should get new value of field mode.
Possible solution:
class ObjectA {
public int Mode { get; set; }
}
class MainClass {
private obj = new ObjectA();
public int Mode {
get { return this.obj.Mode; }
set { this.obj.Mode = value; }
}
}
There is another option in case field mode belongs to MainCalss.
class ObjectA {
private int mode;
public ObjectA(int mode) {
this.mode = mode;
}
// you can create property instead of method
// I'm not sure how you use this variable, so I just added set method
public void SetMode(int mode) {
this.mode = mode;
}
}
class MainClass {
private int mode = 0;
private obj = new ObjectA();
public int Mode {
get { return this.mode; }
set {
this.obj.SetMode(value);
this.mode = value;
}
}
}

How to print just value to label from textbox in winforms?

I'm writing a name generator, and want to add functionality to add new names and surnames to database, but when I'm trying to print values added after running program, I got whole path. For example: I want to add name John. When generator picks John it's printing Windows.Forms.TextBox, Text:John instead of just name. How can I fix this? Here's the code:
using System;
using System.Collections.Generic;
using System.Windows.Forms;
namespace NameGen
{
public partial class Form1 : Form
{
public Generate gen = new Generate();
public Form1()
{
InitializeComponent();
}
private void StartGenerate(object sender, EventArgs e)
{
lblWynik.Text = Generate.NameGen() + " " + Generate.SurnameGen();
Console.WriteLine("Generating: " + lblWynik.Text);
}
private void AddName(object sender, EventArgs e)
{
Generate.LName.Add(NameBox.ToString());
Console.WriteLine("Adding new name to index " + NameBox);
NameBox.Clear();
}
private void AddSurname(object sender, EventArgs e)
{
Generate.LSurname.Add(SurnameBox.ToString());
Console.WriteLine("Adding new surname to index " + SurnameBox);
SurnameBox.Clear();
}
}
public class Generate
{
static string[] Name = new string[] { "Hank", "Terrence", "Darin", "Alf" };
static string[] Surname = new string[] { "Cooper", "Trump", "Białkov", "Obama" };
public static List<string> LName = new List<string>();
public static List<string> LSurname = new List<string>();
static Random random = new Random();
public static string NameGen()
{
LName.AddRange(Name);
int NameIndex = random.Next(LName.Count);
return LName[NameIndex];
}
public static string SurnameGen()
{
LSurname.AddRange(Surname);
int NameIndex = random.Next(LSurname.Count);
return LSurname[NameIndex];
}
}

To get the text of a TextBox you should use Text property of TextBox. For example: Generate.LName.Add(NameBox.Text);
Now you are using ToString method of TextBox which returns the type name and the text.

Using OpenFileDialog and StreamReader

There are two classes, one to cover the form (class 1) and the other to cover what gets displayed on the form (class 2). I'm trying to call a method in class 1 from class 2 to display certain information in a text box. I keep getting the error:
An object reference is required for the non-static field, method, or property
I've encountered this error before and been able to make it through, but nothing I've attempted so far has helped in this instance. I'm posting code for both the classes.
Class 1:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Forms;
namespace Project6
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
Stream myStream = null;
//Create an instance of the open file dialog box
OpenFileDialog ofd = new OpenFileDialog();
//Set parameters, filter options, and filter index
ofd.InitialDirectory = "c:\\";
ofd.Filter = "Text Files (.txt)|*.txt";
ofd.FilterIndex = 2;
ofd.Multiselect = false;
if (ofd.ShowDialog() == DialogResult.OK)
{
try
{
if ((myStream = ofd.OpenFile()) != null)
{
using (myStream = ofd.OpenFile())
{
StreamReader reader = new StreamReader(myStream);
string studentInformation = "";
string[] studentInformationArray = new string[11];
studentInformation = reader.ReadLine();
while ((studentInformation = reader.ReadLine()) != null)
{
studentInformationArray = studentInformation.Split(',');
Student newStudent = new Student(studentInformationArray);
}
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error: Could not read file from disk. Original error: " + ex.Message);
}
}
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
textBox1.Text = Student.GetName(); //This generates the compiler error
textBox1.Select(6, 5);
MessageBox.Show(textBox1.SelectedText);
}
}
}
Class 2:
using System;
using System.Windows.Forms;
namespace Project6
{
class Student
{
//Initialize variables
private string[] studentInformationArray;
//Constructor that accepts the studentInformationArray as an argument
public Student(string[] studentInformationArray)
{
this.studentInformationArray = studentInformationArray;
}
public Student()
{
string className = studentInformationArray[1];
string semester = studentInformationArray[2];
string picture = studentInformationArray[3];
int project1 = Convert.ToInt32(studentInformationArray[4]);
int project2 = Convert.ToInt32(studentInformationArray[5]);
int project3 = Convert.ToInt32(studentInformationArray[6]);
int project4 = Convert.ToInt32(studentInformationArray[7]);
int project5 = Convert.ToInt32(studentInformationArray[8]);
int project6 = Convert.ToInt32(studentInformationArray[9]);
int midtermExam = Convert.ToInt32(studentInformationArray[10]);
int finalExam = Convert.ToInt32(studentInformationArray[11]);
}
public string GetName()
{
string studentName;
studentName = studentInformationArray[0];
return studentName;
}
}
}

That's because that's not how you use the OpenFileDialog. Take a look at this example hosted by the MSDN here:
Edit: answering to your edited question. You will always get a NullReferenceException in the Student() constructor because you are never assigning something to your studentInformationArray. So you can fix it like this:
public Student()
{
studentInformationArray = new studentInformationArray[12];
string className = studentInformationArray[1];
// rest of your code...
}
However, you should take into account that studentInformationArray will be an empty array unless you assign something to it. Since you have a Student() overload that takes a string[], I'd suggest you that you either remove the default constructor or make it call the overloaded with default information, like this:
public Student(string[] studentInformationArray)
{
string className = studentInformationArray[1];
// rest of your code...
int project1 = int.Parse(studentInformationArray[4]); // always prefer int.Parse() instead of Convert.ToInt32()
// rest of your code...
this.studentInformationArray = studentInformationArray;
}
public Student()
{
string[] defaultInformation = new string[12];
// add information
defaultInformation[0] = "some information";
// ...
new Student(defaultInformation);
}
Some more points to take into account:
Class-level fields/properties should be spelled in Pascal Case (first letter of each word in uppercase, rest in lowercase)
Try to never use this.variableName = variableName.
Variables names should never include the type of the variable, that's redundant.
So, for example, change this:
private string[] studentInformationArray;
for this:
private string[] StudentInformation;
Answering your last question, regarding the compiler error, you need a reference to the Student read in order to get its name. You could do something like this:
public partial class Form1 : Form
{
private Student StudentRead;
// rest of your code...
// from your read method:
StudentRead = new Student(studentInformationArray);
// and finally:
private void textBox1_TextChanged(object sender, EventArgs e)
{
textBox1.Text = StudentRead.GetName();

C# delegates problem

I am getting the following error from my C# Windows Application:
Error 1 No overload for 'CreateLabelInPanel' matches delegate 'WorksOrderStore.ProcessDbConnDetailsDelegate' H:\c\WorksOrderFactory\WorksOrderFactory\WorksOrderClient.cs 43 39 WorksOrderFactory
I have 3 .cs files that essentially:
Opens a windows
Has an option for the users to connect to a db
When that is selected, the system will go off and connect to the db, and load some data in (just test data for now)
Then using a delegate, the system should do soemthing, which for testing will be to create a label. However I haven't coded this part yet.
But I can't build until I get this error sorted.
The 3 fiels are called:
WorksOrderClient.cs (which is the MAIN)
WorksOrderStore.cs
LoginBox.cs
Here's the code for each file:
WorksOrderClient.cs:
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;
using WorksOrderStore;
namespace WorksOrderFactory
{
using WorksOrderStore;
public partial class WorksOrderClient : Form
{
LoginBox lb = new LoginBox();
private static WorksOrderDB wodb = new WorksOrderDB();
private static int num_conns = 0;
public WorksOrderClient()
{
InitializeComponent();
}
private void connectToADBToolStripMenuItem_Click(object sender, EventArgs e)
{
lb.ShowDialog();
lb.Visible = true;
}
public static bool createDBConnDetObj(string username, string password, string database)
{
// increase the number of connections
num_conns = num_conns + 1;
// create the connection object
wodb.AddDbConnDetails(username, password, database, num_conns);
// create a new delegate object associated with the static
// method WorksOrderClient.createLabelInPanel
wodb.ProcessDbConnDetails(new ProcessDbConnDetailsDelegate(CreateLabelInPanel));
return true;
}
static void CreateLabelInPanel(DbConnDetails dbcd)
{
Console.Write("hellO");
string tmp = (string)dbcd.username;
//Console.Write(tmp);
}
private void WorksOrderClient_Load(object sender, EventArgs e)
{
}
}
}
WorksOrderStore.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using WorksOrderFactory;
namespace WorksOrderStore
{
using System.Collections;
// Describes a book in the book list:
public struct WorksOrder
{
public string contractor_code { get; set; } // contractor ID
public string email_address { get; set; } // contractors email address
public string date_issued { get; set; } // date the works order was issued
public string wo_ref { get; set; } // works order ref
public string status { get; set; } // status ... not used
public job_status js { get; set; } // status of this worksorder within this system
public WorksOrder(string contractor_code, string email_address, string date_issued, string wo_ref) : this()
{
this.contractor_code = contractor_code;
this.email_address = email_address;
this.date_issued = date_issued;
this.wo_ref = wo_ref;
this.js = job_status.Pending;
}
}
// Declare a delegate type for processing a WorksOrder:
//public delegate void ProcessWorksOrderDelegate(WorksOrder worksorder);
// Maintains a worksorder database.
public class WorksOrderDB
{
// List of all worksorders in the database:
ArrayList list = new ArrayList();
// Add a worksorder to the database:
public void AddWorksOrder(string contractor_code, string email_address, string date_issued, string wo_ref)
{
list.Add(new WorksOrder(contractor_code, email_address, date_issued, wo_ref));
}
// Call a passed-in delegate on each pending works order to process it:
/*public void ProcessPendingWorksOrders(ProcessWorksOrderDelegate processWorksOrder)
{
foreach (WorksOrder wo in list)
{
if (wo.js.Equals(job_status.Pending))
// Calling the delegate:
processWorksOrder(wo);
}
}*/
// Add a DbConnDetails to the database:
public void AddDbConnDetails(string username, string password, string database, int conn_num)
{
list.Add(new DbConnDetails(username, password, database, conn_num));
}
// Call a passed-in delegate on each dbconndet to process it:
public void ProcessDbConnDetails(ProcessDbConnDetailsDelegate processDBConnDetails)
{
foreach (DbConnDetails wo in list)
{
processDBConnDetails(wo);
}
}
}
// statuses for worksorders in this system
public enum job_status
{
Pending,
InProgress,
Completed
}
public struct DbConnDetails
{
public string username { get; set; } // username
public string password { get; set; } // password
public string database { get; set; } // database
public int conn_num { get; set; } // this objects connection number.
public ArrayList woList { get; set; } // list of works orders for this connection
// this constructor just sets the db connection details
// the woList array will get created later .. not a lot later but a bit.
public DbConnDetails(string username, string password, string database, int conn_num) : this()
{
this.username = username;
this.password = password;
this.database = database;
this.conn_num = conn_num;
woList = new ArrayList();
}
}
// Declare a delegate type for processing a DbConnDetails:
public delegate void ProcessDbConnDetailsDelegate(DbConnDetails dbConnDetails);
}
LoginBox.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WorksOrderFactory
{
public partial class LoginBox : Form
{
public LoginBox()
{
InitializeComponent();
}
private void LoginBox_Load(object sender, EventArgs e)
{
this.Visible = true;
this.Show();
//usernameText.Text = "Username";
//new Font(usernameText.Font, FontStyle.Italic);
}
private void cancelBtn_Click(object sender, EventArgs e)
{
this.Close();
}
private void loginBtn_Click(object sender, EventArgs e)
{
// set up a connection details object.
bool success = WorksOrderClient.createDBConnDetObj(usernameText.Text, passwordText.Text, databaseText.Text);
}
private void LoginBox_Load_1(object sender, EventArgs e)
{
}
}
}
Any ideas??
Cheers,
m

The one thing jumps out when comparing the definition of the delegate with the definition of the method you're trying to use:
static void CreateLabelInPanel(DbConnDetails dbcd)
public delegate void ProcessDbConnDetailsDelegate(DbConnDetails dbConnDetails)
CreateLabelInPanel should probably not be declared as static.

The compiler is just saying that the method you are providing to a delegate is not matching the signature expected by the delegate.
So, in your case.
//To get this line working...
wodb.ProcessDbConnDetails(new ProcessDbConnDetailsDelegate(SomeMethod1));
//The method signature should be like this.
static void SomeMethod1(DbConnDetails dbcd)
//OR even this -- Instance/Static methods can be supplied to same delegate.
void SomeInstanceMethod(DbConnDetails dbcd)..
And if not, the compiler would complain.
Also, by any chance, do you have two classes with the name "DbConnDetails" ???
My best guess is you are referring to "DbConnDetails" that lies in different namespace than the one expected by the delegate.

thanks #amby and #massif and anyone else I may have missed.
This was a school boy error.
It turns out I had another file (which I thought I'd deleted) that also contained a class and constructor called DbConnDetails. I did a search for DbConnDetails in the solution.
I renamed that class/constructor and the filename as well, to be safe.
I then declared
static void CreateLabelInPanel(DbConnDetails dbcd)
which means that the app now compiles/builds again.
Thanks again to everyone.

TextBox not updating in C#

Specifically looking at the arrive method in the Customer class. I am using a for loop to create instances of the customer class, and when I try to write out their arrival times to a textBox (Just for testing purposes) the text box does not update. Why is this?
This is just a small simulation project for my Computing class. It is in its early stages, and is probably wrong in a lot of places!
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;
using System.Threading;
namespace QueueSimulation
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
public void Form1_Load(object sender, EventArgs e)
{
MessageBox.Show("The form has loaded");
}
public void goButton_Click(object sender, EventArgs e)
{
Initialisers init = new Initialisers();
Customer customer = new Customer();
customer.Arrive();
}
private void stopButton_Click(object sender, EventArgs e)
{
// put code here to break out of the program
}
}
public class Customer : Initialisers
{
int waitingTime;
int arrivalTime;
int arrivalInterval;
Initialisers init = new Initialisers();
public void Arrive()
{
Customer[] customer = new Customer[1000];
int counter = 0;
for (int i = 1; i <= 10; i++)
{
customer[i] = new Customer();
customer[i].TimeArrived();
displayArrival.Text = displayArrival.Text + customer[i].TimeArrived().ToString();
// Implement something to either show the time in the queue if needed
Thread.Sleep(init.CustomerArriveTime*100);
}
MessageBox.Show("All of the customers have arrived");
}
public string TimeArrived()
{
return Convert.ToString(DateTime.Now);
}
public void Leave()
{
}
public void GetServed()
{
}
}
public class Server
{
bool servingStatus;
int servingTime;
public void Serve()
{
}
}
public class Initialisers : Form1
{
private int cust_no = 3;
public int CustomerArriveTime
{
get
{
return cust_no;
}
set
{
cust_no = value;
}
}
private int s_time = 4;
public int serveTime
{
get
{
return s_time;
}
set
{
s_time = value;
}
}
}
}

Pass to the Arrive the instance of the textbox object created on your Form1.
public void Arrive(TextBox displayArrival)
Why are you inheriting the Form1 in Initialiserz? It's better to pass the reference to Form1 instead of inheritance in this case.

This seems overly complex. Try to model the real world. What is Initialisers, and why do you have an inheritance tree: Customer > Initialisers > Form1?
You're customer is writing to its own TextBox, instead of the TextBox you're looking at (the one from the Form that is visible).
Why not have a method Arrive that sets a private field to DateTime.Now. Then, ask the Customer its TimeArrived, which returns this field. In your Form, call these methods as much as needed in your loop.
This also seperaties command (Arrive) from query (TimeArrived) + keeps your inheritance more logical.
You might not even need Initialisers anymore. And don't let Customer inherit from Form, because a Customer isn't a Form.

I think there is more of a design issue here, you are creating instances of customer inside customer.
Your customer Arrive method should probably be a function inside the another class, like below, customer should just define what a customer is. Processing them should be handled by a different class.
class Customer
{
int waitingTime;
int arrivalTime;
int arrivalInterval;
// etc...
}
class ProcessCustomers
{
pubic void Arrive()
{
// etc...
}
}
public void goButton_Click(object sender, EventArgs e)
{
Initialisers init = new Initialisers();
ProcessCustomers CustomerQueue = new ProcessCustomers();
CustomerQueue .Arrive();
}
But for the text box issue you will have to expose a property in the form class and set it like that,
string ArrivalTime
{
get
{
return textBox1.Text;
}
set
{
textBox1.Text = value;
}
}