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GeneralHelp in C # Pin
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QuestionHow to check whether Datetime value is null Pin
YAI17-Apr-08 18:11
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AnswerRe: How to check whether Datetime value is null Pin
Christian Graus17-Apr-08 19:42
protectorChristian Graus17-Apr-08 19:42 
GeneralRe: How to check whether Datetime value is null Pin
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sitebuilderLuc Pattyn17-Apr-08 21:11 
GeneralNullReferenceException when using Delegate Pin
cocoonwls17-Apr-08 15:30
cocoonwls17-Apr-08 15:30 
Hi all,
In my application, i have few delegate and it is work well,but one of the delegate prompt me the error below when using delegate to pass data from frmA to frmB:

NullReferenceException was unhandled
Object reference not set to an instance of an object.


Below is the sample coding:

formA:
public openForm callbackOpenForm;
public DisplayProgramNameDate callbackProName;
public openExistingProgram callbackExistProgram;

public formA{}

private void btnOpen_open_Click(object sender, EventArgs e)
{
    callbackProName(cboProgram_open.Text, Convert.ToString(DateTime.Now));
    callbackOpenForm("ProgramSetting");
    callbackExistProgram();  <----------------------error on this delegate
    this.Hide();
}


formB:
public formB{
          formA fA = new formA();
          fA.callbackExistProgram += new openExistingProgram(this.callbackExistProgramFn);
        }

        private void callbackExistProgramFn()
        {
            sqlconn.DbConnection();
            ds = sqlconn.SelectSQL("ProgramSetting", "PS_Program_Name", singleton.ProName);
        }


class Delegate:
//create new drawing area at main
public delegate void CreatePictureBox(Boolean b);
//display pro name in statusstrip at main
public delegate void DisplayProgramNameDate(String sName, String sDate);
//call to open form
public delegate void openForm(String sName);
//Open a program
public delegate void openExistingProgram();

can anyone help me on this? Sigh | :sigh:


thanks in advance
cocoon
GeneralRe: NullReferenceException when using Delegate Pin
Christian Graus17-Apr-08 15:37
protectorChristian Graus17-Apr-08 15:37 
GeneralRe: NullReferenceException when using Delegate Pin
cocoonwls17-Apr-08 16:12
cocoonwls17-Apr-08 16:12 
GeneralRe: NullReferenceException when using Delegate Pin
Christian Graus17-Apr-08 16:22
protectorChristian Graus17-Apr-08 16:22 
GeneralMadness? IDisposable and template/factory methods Pin
Roger Alsing17-Apr-08 12:44
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QuestionI am getting 0x00000096 type messages. Pin
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QuestionHow to change the "Close" text string which is displayed when the user hovers over the Windows Form ControlBox 'X' Close button Pin
jack8091817-Apr-08 10:08
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AnswerRe: How to change the "Close" text string which is displayed when the user hovers over the Windows Form ControlBox 'X' Close button Pin
Ravenet17-Apr-08 15:41
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QuestionConfig file in DLL C# projects Pin
ARol17-Apr-08 9:15
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Generalthe problem write to file is still continuing:( Pin
wwwxyz17-Apr-08 8:52
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BoneSoft17-Apr-08 11:49
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GeneralRe: the problem write to file is still continuing:( Pin
wwwxyz17-Apr-08 19:41
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GeneralRe: the problem write to file is still continuing:( Pin
wwwxyz17-Apr-08 19:59
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GeneralRe: the problem write to file is still continuing:( Pin
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GeneralDataTable remains empty on button finish click Pin
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