C / C++ / MFC

Re: Some value (ascii I suppose) instead of the character

10-Nov-07 14:01

There is to my knowledge no MFC etc function available to do this. But, hey, you effectively rolled your own parser! That means that you have to write all functions to deal with stuff that XML can throw at it. If you leave something out, you will sooner or later become a cropper. The writing of a function to convert the simple escapes you mentioned appears to me to be a relatively minor issue in the greater scheme of things you are taking on.

regards, Smile | :)

Bram van Kampen

bob1697210-Nov-07 18:46

bob16972

10-Nov-07 18:46

shpid3r wrote:
to be honest I`m not sure I know exactly what`s the difference between encodings

If your going to parse XML from a windows box and attempt to do something with the data, you will need to understand the differences between UTF-8, UTF-16, UCS-2, and code pages if your compiling for MBCS. There is no compromise on this if you want your parser to work and your results to display correctly, without corruption in your Visual C++ program.

Even from my little experience in XML processing, it is obvious based on your post that you are attempting to tackle a non-trivial subject with a trivial approach thats likely to end in frustration. Do yourself a favor and use an already existing and well supported XML parser. You will still likely need to understand encodings anyway, but it will save you a lot of headaches early on.

ON_COMMAND_RANGE()

thes3cr3t110-Nov-07 1:39

thes3cr3t1

10-Nov-07 1:39

ON_COMMAND_RANGE(IDC_RELAY1, IDC_RELAY8, ChangePin)

hi there,

the Above code will call the function ChangePin() when checkbox's in the range IDC_RELAY1 to IDC_RELAY8 are changed, can anybody tell me what kind of message is sent when a user clicks one of the checkbox's?

i am trying to progmaticaly send the "BN_CLICKED" message to trigger the ChangePin function from my code without having to physicaly use the mouse to heck the checkbox.

thanks chris

Re: ON_COMMAND_RANGE()

chandu00410-Nov-07 1:45

chandu004

10-Nov-07 1:45

try simply checking the checkbox programatically and see.
AFAIK that should automatically call the associated function.
good luck.

--------------------------------------------
Suggestion to the members:
Please prefix your main thread subject with [SOLVED] if it is solved.
thanks.
chandu.

Re: ON_COMMAND_RANGE()

thes3cr3t110-Nov-07 2:14

thes3cr3t1

10-Nov-07 2:14

i tried checking the checkbox,by setting its value to TRUE,and then Updating the dialog using UpdateData(false); sure enough the checkbox checked but it failed to call the ChangePin function.

any other idieas?

thanks
chris

Re: ON_COMMAND_RANGE()

Mark Salsbery10-Nov-07 5:41

Mark Salsbery

10-Nov-07 5:41

You can always use SetCheck() to change the check state of the
checkbx then call ChangePin direcly, passing the id of the checkbox.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Equal compare

George_George10-Nov-07 0:23

10-Nov-07 0:23

Hello everyone,

I want to confirm that on a 32-bit machine,

1. compare the value of two byte to see whether they are equal or not;
2. compare the value of two integer (4-byte) to see whether they are equal or not.

(1) and (2) should have the same performance, right? I am using x86 32bit Windows machine to develop native unmanaged C++ application.

thanks in advance,
George

Bram van Kampen10-Nov-07 13:49

10-Nov-07 13:49

Depends a bit on allignment,and on the precise processor on the target machine, but the difference should be insignificant for most purposes.

regards Smile | :)

Bram van Kampen

George_George10-Nov-07 23:41

10-Nov-07 23:41

Hi Bram,

I am interested to learn what do you mean alignment. Could you provide more information please?

regards,
George

Bram van Kampen12-Nov-07 16:33

12-Nov-07 16:33

Allignment Cry | :((

I thought this was a quite Basic, Simple and well understood topic, but I must admit, cannot find any articles about it. Must write a short one myself to fill this void. Watch this space, and I get something together soon.

Regards,

Bram van Kampen

George_George12-Nov-07 19:54

12-Nov-07 19:54

Hi Bram van Kampen,

I am not saying that I do not understand what is memory alignment. Smile | :)

My question is I do not know why you mentioned memory alignment matters to the performance of equal comparison in my question. Could you provide more information please?

regards,
George

JudyL_MD13-Nov-07 2:00

JudyL_MD

13-Nov-07 2:00

If the item being compared is less than the natural word size in the CPU, the item may need to be shifted before the comparison takes place. That takes more time than if the item falls on a natural word boundary.

Judy

George_George14-Nov-07 1:01

14-Nov-07 1:01

Thanks Judy,

I do not know why if loading one byte, other than 4-bytes (32-bit), the system needs additional efforts to do alignment? For one byte, the system can load the continuous 4 bytes from memory which contains the one byte and could meet with 32-bit alignment requirement, and in this way, only one CPU cycle is needed, and no additional cycle is needed to do alignment for 4-byte (32-bit) data, right?

Please correct me if there are anything wrong with my statements above. Smile | :)

regards,
George

JudyL_MD14-Nov-07 3:32

JudyL_MD

14-Nov-07 3:32

Read Bram's post again more carefully. The difference comes in if the item to be compared is not one byte long and is not stored on a 4-word boundary. If the item is 4 bytes long but is not aligned on the boundary, the CPU must do two fetches to get the item in its entirety before it can compare.

Judy

Bram van Kampen14-Nov-07 15:45

14-Nov-07 15:45

Thanks, At least You Understand what I'm trying to explain. You confirmed I'm Not writing gibberish afterall. Trying to close the tread , without success sofar.

We were all learners once.

Regards and thanks

Bram van Kampen

George_George14-Nov-07 18:11

14-Nov-07 18:11

Hi Judy,

In my original question, I am comparing one byte with another one byte. So, I do not think there is any alignment issues. Bram is talking about if a WORD or something is put across the alignment boundary, so we need to 2 CPU cycles to fetch -- it is another case. I am talking about a byte, not a WORD.

Please feel free to correct me if I am wrong. Smile | :)

If we need any additional alignment operations for one byte (not one WORD or DWORD), please also correct and I would be willing to learn.

regards,
George

JudyL_MD15-Nov-07 2:57

JudyL_MD

15-Nov-07 2:57

You are correct for a byte. Your original post way back when also mentioned an int which is not one byte so you got the long discussion on alignment. This statement concerns me:

George_George wrote:
If we need any additional alignment operations for one byte (not one WORD or DWORD), please also correct and I would be willing to learn.

You do not do anything to deal with alignment with respect to the CPU, it handles that itself. You asked a pretty low level performance question about the comparison of two one-byte numbers versus the comparison of two four-byte numbers. You got a low-level answer on how the CPU handles these comparisons which is where the answer to your original performance question lies.

The alignment Bram and I have been talking about is not the same as the "struture member alignment" option you can specify in the compiler options and override with #pragma pack. Two completely different beasts.

The first answer when dealing with a question about low-level performance should always be: code it in a sane and reasonable manner without trying to optimize performance and see how it actually performs before tinkering with the code. Nine times out of ten, it performs fine. In the one case where it doesn't, do some profiling and see where the bottlenecks actually are. They are usually not where you were worrying about in the first place.

Judy

George_George18-Nov-07 4:32