Re: Cannot perform '=' operation on System.Char and System.Boolean. exception - C# Discussion Boards

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

27-Aug-09 21:41

Hi all,

I am developing a winforms application and, in order to store some data on the client side I am using a dataset. My problem is that for a particular table (nothing different in settings compared to other datatables in my dataset), I get an exception when I try to insert a new Row.
I will not paste any code in here as I don't think that it will help anyone, but what I do is:

* create new row object using: MyDataSet.MyDatatableRow row = datasetInstance.MyDataTable.NewMyDataTableRow();
* I populate the columns I need
* I try to add the row to the datatable: datasetInstance.MyDataTable.AddMyDataTableRow(row);

At the very last step (add to datatable), I get an exception saying: "Cannot perform '=' operation on System.Char and System.Boolean."
I tried to see if I am doing something wrong while setting the column value, but everything looks fine... also I already waste lots of time on google trying to find an answer, but no success.

Can anyone explain to me why this exeption occurs? Any idea what could be wrong, what should I try in order to fix this?

Thank you in advance!

Andrei

Vimalsoft(Pty) Ltd27-Aug-09 22:10

Vimalsoft(Pty) Ltd

27-Aug-09 22:10

Can we see the code ?

Vuyiswa Maseko,

Few companies that installed computers to reduce the employment of clerks have realized their expectations.... They now need more and more expensive clerks even though they call them "Developers" or "Programmers."

C#/VB.NET/ASP.NET/SQL7/2000/2005/2008
http://www.vuyiswamaseko.com
vuyiswa@its.co.za
http://www.itsabacus.co.za/itsabacus/

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

acroitoriu27-Aug-09 22:30

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

27-Aug-09 22:30

To be honest, I don't see how this will help. Besides the code (which is quite long as there is business logic), I should paste also the datatable structure. Anyway, I have similar logic with many other datatables in the dataset, and I didn't get this exception so far. If you think that this is related to the way I populate the data, I will try to prepare the copy of my code and maybe a description of the datatable structure in case you think it will help.

DaveyM6927-Aug-09 23:08

DaveyM69

27-Aug-09 23:08

Well most likely, you are trying to store a boolean value in a field that takes char. Without code or a crystal ball I don't see how we can offer any more help. Just post the relavent bits (in <pre></pre> tags). Stripping out some of the chaff and validation/business logic will not only make it readable, but you might see where the problem lies.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)
Why are you using VB6? Do you hate yourself? (Christian Graus)

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

Luc Pattyn28-Aug-09 0:36

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

28-Aug-09 0:36

Someone has to check the code, if you don't, and you don't publish any, who will?

here is a twin suggestion:
- exceptions most often contain file name, line number and method name information; to see it all, make sure you output Exception.ToString() and not just Exception.Message
- your IDE is capable of showing line numbers in all editor windows; make sure to switch that on. For Visual Studio, see here[^].

Smile | :)

Luc Pattyn

Badger | [badger,badger,badger,badger...]

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

acroitoriu28-Aug-09 0:56

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

28-Aug-09 0:56

... thanks for the tips Smile | :)

I use them for a few years now + log4net to print exception. However, it's the first time when I get this exception - EVER! As soon as I will get 10-15 minutes free I will strip the code of business logic and post it here.

Luc Pattyn28-Aug-09 1:28

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

28-Aug-09 1:28

so you know what line is failing Confused | :confused:

Luc Pattyn

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

acroitoriu28-Aug-09 1:33

Re: Cannot perform '=' operation on System.Char and System.Boolean. exception

28-Aug-09 1:33

Yes, as I initially mention, the exception occurs when the AddMyDataTableRow method is called. When I say AddMyDataTableRow I mean the datatable specific method that is generated for every datatable to add new row: AddxxxRow

acroitoriu30-Aug-09 3:06

30-Aug-09 3:06

OK, problem fixed. By some stupid mistake a field was defined as char in the datatable, but it was used as boolean in an expression. After fixing this issue everything worked fine.

messagbox

sanforjackass27-Aug-09 20:19

sanforjackass

27-Aug-09 20:19

how can i make the the font of text in messagbox as i want?

stancrm27-Aug-09 21:04

MessageBoxManager - A Windows Forms component that provides enhanced MessageBox functionality[^]

27-Aug-09 21:04

sanforjackass28-Aug-09 0:30

sanforjackass

28-Aug-09 0:30

i want it in c#

stancrm28-Aug-09 0:35

28-Aug-09 0:35

That is in C#

EliottA28-Aug-09 2:37

EliottA

28-Aug-09 2:37

Ha.

Check out the CodeProject forum Guidelines[^]
The original soapbox 1.0 is back![^]

Luc Pattyn28-Aug-09 0:38

How to Scale an image to its real world size

28-Aug-09 0:38

if you're not satisfied by some simple component, such as MessageBox, roll your own. It ain't hard at all. It is easier than getting it to do what you want against it's own will.

Smile | :)

Luc Pattyn

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.

jamesjk27-Aug-09 20:11

jamesjk

27-Aug-09 20:11

Hi,

I have images of human body parts. Is it possible to view the image at its actual real world size.

How can I achieve this ?
How do I confirm whether current size of the image is same as its real world size?

Thanks in advance for all the help & suggestions.....

stancrm27-Aug-09 21:01

27-Aug-09 21:01

You must get the DPI. For example the picture has 96dpi and the size is 1024x768 pixel.

1024/96 -> 10.67 inch
768/96 -> 8 inch

That means : the print size is 10.67 x 8 inch

jamesjk27-Aug-09 21:49

jamesjk

27-Aug-09 21:49

thanks stancrm,

will this ensure that the image, say that of a knee will be exactly of the same size of the person's knee whose knee was pictured ?

stancrm27-Aug-09 22:09

27-Aug-09 22:09

if you have a camera that can take a picture 1:1, then yes...

Luc Pattyn28-Aug-09 0:46

28-Aug-09 0:46

Hi,

you will need the following:

1. most camera's generate JPG files, with embedded tags containing a lot of parameters;

2. GDI+ can paint images at their actual size, see Graphics.DrawImageUnscaled;

3. your system has a DPI setting (defaults to 96) which you can change to correspond to the actual resolution (in dpi) of your monitor; you can calculate the required value like so:
Math.Sqrt(screenWidthPixels^2+screenHeightPixels^2)/screenDiagonalInches*100/96

the square root calculates number of pixels on the diagonal;
the final 100/96 is needed because Windows expects the number as a percentage of 96dpi, the default value.

You may be a bit out of luck if you use multiple monitors with different DPI values.

4. Your printer drivers should take care of DPI settings all by themselves.

Smile | :)

Luc Pattyn

Have a look at my entry for the lean-and-mean competition; please provide comments, feedback, discussion, and don’t forget to vote for it! Thank you.