Re: How to pass null ref type. - C# Discussion Boards

Re: How to fetch the user filled fields in PDF form

Wonde Tadesse6-Dec-11 13:09

Wonde Tadesse

6-Dec-11 13:09

Have a look at this article.Extract All Form Fields From Pdf File Using C # and IText Sharp Library[^]

Wonde Tadesse
MCTS

Re: How to fetch the user filled fields in PDF form

Ravi k rao6-Dec-11 21:25

Ravi k rao

6-Dec-11 21:25

Thanks for your reply, but i need to fetch the user filled fields.
Is there any way to fetch those field values/tables?

How to pass null ref type.

__John_6-Dec-11 3:18

__John_

6-Dec-11 3:18

Hi,

I am hosting an ActivX control in C#. The control has a method as follows...

GetMinMaxVals(bouble* pdMinX, double* pdMaxX, double* pdMinY, double* pdMaxY);

The caller may pass null (zero) for any of the parameters that are not required. I only need a value for pdMaxX.

Question is: How do I pass null for the arguments i do not require?

Thanks - John.

Re: How to pass null ref type.

Luc Pattyn6-Dec-11 4:17

Luc Pattyn

6-Dec-11 4:17

I don't see a problem. What does your code look like? What have you tried? How does it fail?

Smile | :)

Luc Pattyn [My Articles] Nil Volentibus Arduum

Re: How to pass null ref type.

BobJanova6-Dec-11 4:21

BobJanova

6-Dec-11 4:21

You may need to declare the parameters as IntPtr not ref double. As far as I'm aware it's not possible to pass a null pointer (as opposed to a pointer to null) through a ref or out parameter – it's rather the point of them to stop you accidentally referencing null pointers, after all.

Re: How to pass null ref type.

__John_6-Dec-11 4:36

__John_

6-Dec-11 4:36

Thanks for the replies,

@Bob, how would I change the argument type to IntPtr (sounds like it could be a solution), when the method is exposed from the interop dll's generated by VisualStudio?

Thanks - John.

Re: How to pass null ref type.

BobJanova6-Dec-11 5:34

BobJanova

6-Dec-11 5:34

You have to manually edit the interop C# it produces, I think. I realise this is non-ideal but tlbimp isn't that clever and it makes assumptions (like pointer -> ref) that aren't necessarily valid, so it's sometimes necessary.

Re: How to pass null ref type.

DaveyM696-Dec-11 7:07

DaveyM69

6-Dec-11 7:07

Just change the DllImport decorated function to use IntPtr instead of double:

// GetMinMaxVals(double* pdMinX, double* pdMaxX, double* pdMinY, double* pdMaxY);
// "I only need a value for pdMaxX"
// No return type in your example was shown so using void here! Change as required.
[DllImport("thedll.dll", SetLastError = true)]
public static extern void GetMinMaxVals(IntPtr pdMinX, ref double pdMaxX, IntPtr pdMinY, IntPtr pdMaxY);

You can then call this like:

double pdMaxX = 0;
GetMinMaxVals(IntPtr.Zero, ref pdMaxX, IntPtr.Zero, IntPtr.Zero);

Change the value of pdMaxX to whatever is suitable for the call. If it only passes a value out and doesn't require one in, then use out instead of ref.

[DllImport("thedll.dll", SetLastError = true)]
public static extern void GetMinMaxVals(IntPtr pdMinX, out double pdMaxX, IntPtr pdMinY, IntPtr pdMaxY);

double pdMaxX;
GetMinMaxVals(IntPtr.Zero, out pdMaxX, IntPtr.Zero, IntPtr.Zero);

If the function returns a value then amend as required.

Dave

Binging is like googling, it just feels dirtier.
Please take your VB.NET out of our nice case sensitive forum.
Astonish us. Be exceptional. (Pete O'Hanlon)

BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)

Re: How to pass null ref type.

Richard MacCutchan6-Dec-11 5:01

Richard MacCutchan

6-Dec-11 5:01

So how does the called routine decide which parameters are required and which are not? You could just as easily pass a ref to some special value (0.0, -1.0 etc).

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Re: How to pass null ref type.

DaveyM696-Dec-11 12:27

DaveyM69

6-Dec-11 12:27

I'm not confident on this as I obviously don't have the OPs code or API for the ActiveX, but I would guess from the info provided that it looks for null pointers, the .NET equivalent of System.IntPtr.Zero.

I've never looked into this, but doesn't a ref parameter marshal the address at which the actual value is stored, therefore passing 0.0 could pass a pointer to any valid memory address rather than a null (zero) pointer? This could be way wrong - I will research!

Re: How to pass null ref type.

Richard MacCutchan6-Dec-11 13:13

Richard MacCutchan

6-Dec-11 13:13

Sorry, I think my comment was not clear. I was suggesting a reference to a variable that contains a specific value that the called method would recognise as a null value. However, the information we have been given seems somewhat less than complete - as is all too common.

Unrequited desire is character building. OriginalGriff
I'm sitting here giving you a standing ovation - Len Goodman

Re: How to pass null ref type.

Peter_in_27806-Dec-11 13:04

Peter_in_2780

6-Dec-11 13:04

[Read this in conjunction with Davey's reply above]
I'm guessing here, but does GetMinMaxVals just return four doubles through the pointers you pass to it?
If so, then just call it with something like GetMinMaxVals(out double junk1, out double MaxX, out double junk2, out double junk3)
In other words, provide four places for it to put the results, and ignore the three you don't need.

Cheers,
Peter

Software rusts. Simon Stephenson, ca 1994.

Re: How to pass null ref type.

__John_7-Dec-11 4:36

__John_

7-Dec-11 4:36

Hi Peter, I am currently doing it the way you sagest, only problem is that it takes time to calculate each value and is making the UI a bit slugg like.

Thanks - John.

Multilingual keyboard support for C# touchscreen application

PetersCodeProject6-Dec-11 3:06

PetersCodeProject

6-Dec-11 3:06

I am looking for either source code or a dll providing a multilingual keyboard for a windows forms C# touchscreen application. This could be either free for commercial use or paid for.

I have spotted the following WEB projects:

1./ A Multilingual Silverlight Virtual Keyboard
2./ JavaScript VirtualKeyboard

but need something non WEB based.

Any pointers would be greatly appreciated.

Run code if event log entry is older than 12 hours - could you help

CCodeNewbie6-Dec-11 0:15

CCodeNewbie

6-Dec-11 0:15

Hi,

I need my windows service to execute a routine depending on how old an entry in the Application event log is, i.e. if the last recorded event id (set by the routine) is older than 12 hours then run the routine again...

so, routine runs and writes...

if (!EventLog.SourceExists("mylog")) EventLog.CreateEventSource("mylog", "Application");
EventLog.WriteEntry("mylog", "routine run" , EventLogEntryType.Information,123456);

then, based on a timer...

DateTime lastexe;
EventLog eLog = new EventLog("Application");
   foreach (EventLogEntry entry in eLog)
   {
      if (!entry.EventID == 123456)
      {
         List<datetime> lastrun = new List<datetime>();// is it best to use a list here?
         lastrun.Add(entry.TimeWritten);
         foreach(entry.TimeWritten in lastrun)//error here "type/identifier both required in foreach statement"
         lastexe = lastrun.FindLast;//or should I use MaxValue?
      }
   }
DateTime shouldrun;
DateTime rt = DateTime.Now;
    if(rt > lastexe.AddHours(1))
    {
    //run routine
    }

As always, your help is appreciated.Thanks.

Re: Run code if event log entry is older than 12 hours - could you help

Eddy Vluggen6-Dec-11 8:07

Eddy Vluggen

6-Dec-11 8:07

CCodeNewbie wrote:
// is it best to use a list here?

Yup.

CCodeNewbie wrote:
foreach(entry.TimeWritten in lastrun)//error here "type/identifier both required in foreach statement"

"entry.timeWritten" isn't a valid variable-name. This is the variable you can use in the loop. It also requires a type for that variable. Since your list is filled with DateTime objects, we can safely assume this type;

foreach(DateTime someDate in lastrun)//no more error :)

CCodeNewbie wrote:
lastexe = lastrun.FindLast;//or should I use MaxValue?

<a href="http://msdn.microsoft.com/en-us/library/5kthb929.aspx">FindLast</a>[<a href="http://msdn.microsoft.com/en-us/library/5kthb929.aspx" target="_blank" title="New Window">^</a>]

returns the last item in the list that qualifies the conditions given.

Try something along these lines;

foreach(DateTime someDate in lastrun)
{
  if (someDate > lastexe) 
  {
    lastexe = someDate;
  }
}

Using LINQ, that code would be effectively reduced to;

DateTime lastexe = lastrun.Max();

Bastard Programmer from Hell Suspicious | :suss:

Linq operation [Grouping and Sum]

nitin_ion5-Dec-11 23:16

nitin_ion

5-Dec-11 23:16

I have a table which has columns like this

EmpID | Hours | Date
1 | 7.5 | 20110105
1 | 7.5 | 20110106
1 | 7.5 | 20110107
1 | 7.5 | 20110108
1 | 7.5 | 20110208

date means 2011-01-05

Now i want to get consolidated record of employees like this

EmpID | Hours | Date
1 | 30 | 01
1 | 7.5 | 02

for this i am using this in linq [of course some joins]

from lev in db.TimeTables
                        where lev.ActualDate.Contains(Year) &&
                        lev.PRJ_InternalID.Equals(36)
                        join
                        emp in db.Employees on lev.EMP_InternalID equals emp.InternalID
                        join
                        prj in db.Projects on lev.PRJ_InternalID equals prj.InternalID
                        select new LastYearVacationDetail
                        {
                            EmployeeID = lev.EMP_InternalID,
                            LeaveDays =  lev.Hours,
                            Month = lev.ActualDate.Substring(5, 2)
                        }).ToList();

Now i am not getting Sum and not able to group.
Any help is appreciated

Re: Linq operation [Grouping and Sum]

OriginalGriff6-Dec-11 1:20

OriginalGriff

6-Dec-11 1:20

You could post this in the Linq forum[^]

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

OpenDialogFile Issue

PDTUM5-Dec-11 7:42

PDTUM

5-Dec-11 7:42

Hello,

I have an application that is composed of 2 forms. The first page launches the second page. On Page 2, I have a "Save As" button that launches a SaveFileDialog box, which works perfectly to save a file. However, whether I save or cancel, after it is done, the application closes Page 2 and restarts on Page 1. I want to application to simply return me to Page 2 where the Save As button is. I have tried several variations but have been unable to make it work that way. I am looking for a piece of code that will allow a new instruction when either Cancel or Save is selected from the SaveFileDialog box. I am including the save dialog code that I am using.

string savedFile = string.Empty;

           // Displays a SaveFileDialog so the user can save the File
           SaveFileDialog saveFD = new SaveFileDialog();
           saveFD.Filter = "Text Files|*.txt|All Files|*.*";
           saveFD.Title = "Save a Text File";

           // If the user does not cancel, open Dialog Box to save the file.
           if (saveFD.ShowDialog() != DialogResult.Cancel)
           {
               savedFile = saveFD.FileName;
               richTextBoxSql.SaveFile(savedFile, RichTextBoxStreamType.PlainText);
           }
           else
           {
              //Code
           }

Any suggestions are gratefully appreciated. Thank You..Pat

Re: OpenDialogFile Issue

fjdiewornncalwe5-Dec-11 8:30

fjdiewornncalwe

5-Dec-11 8:30

The code you have provided is fine and will not cause the form that calls this code to close. You must have this save as button set as the Accept or Cancel button for the form, or the button click handler contains the formname.close call.

I wasn't, now I am, then I won't be anymore.

Re: OpenDialogFile Issue

PDTUM5-Dec-11 12:29

PDTUM

5-Dec-11 12:29

Great Call Marcus....definitely a case of not being able to see the forest through the trees! I have this very poor habit of copying controls rather than making new one's, caused by my laziness when it comes to having to format. I may have done that with this button (or something else as foolish) and somehow managed to assign it the Cancel event. I gratefully gave you a fast five for this one. Best to all that replied. I truly do appreciate it. Luc...thank you for your input. Nice to see you replying to me again...Pat

Re: OpenDialogFile Issue

OriginalGriff5-Dec-11 8:37

OriginalGriff

5-Dec-11 8:37

I tried pasting your code into a form, and displaying the form via both Show and ShowDialog. Even with an AcceptButton and a CancelButton defined, I could not make it close the form by closing the SaveFileDialog with the mouse on either button, or with the ENTER or ESC keys.

In short - I cannot duplicate your problem from the information you have given. What are you doing that I am not? Have you tried removing code until it does work, then putting it back until it stops again?

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

Re: OpenDialogFile Issue

Luc Pattyn5-Dec-11 10:11

Luc Pattyn

5-Dec-11 10:11

OriginalGriff wrote:
Have you tried ... putting it back until it stops again?

Now why would he want to do that? Laugh | :laugh:

Seriously, removing code to deal with a bug is fine, most bugs are in code you don't really need anyway; putting the bugs back in is a bit weird though.

Luc Pattyn [My Articles] Nil Volentibus Arduum

Re: OpenDialogFile Issue

OriginalGriff5-Dec-11 20:47

OriginalGriff

5-Dec-11 20:47

Take away in huge chunks: problem goes away. Put back smaller chunks: problem comes back. Your bug is now in a smaller bit of code, so repeat the process until you have a manageable code size that demonstrates the problem.

I do like to be able to replicate bugs before I try to fix them... Big Grin | :-D

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

Re: OpenDialogFile Issue

BillWoodruff6-Dec-11 9:54

BillWoodruff

6-Dec-11 9:54

Got my five on this one, which I think deserves posterity via some "idiom."

My suggestion: "kill code until live: resurrect code until death."

Actually it's a technique I use quite often to isolate bugs, along with trying to reproduce the bug "outside" the original context by creating a special test-case mini-app, or replacement class, or whatever.

Smile | :)

best, Bill

"Anyone who shows me my 'blind spots' gives me the gift of sight." ... a thought from the shallows of the deeply shallow mind of ... Bill

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.