C / C++ / MFC

12-Aug-02 8:10

I am converting a UNIX application to Windows using VC++ and MFC. There are a large number of printf statements in the code, so I re-defined the printf function, with vsprintf, so that all text will go to a richedit control.

The problem I face is that when a data file is read, it is possible that one of the fields will have a "%" sign as part of its value. When this value is displayed, it looks as though vsprintf is behaving as documented and printing the value without the % sign. Does anyone know of an easy, efficient way to make sure the % sign is printed as well?

Thanks,

Shawn

Tomasz Sowinski12-Aug-02 8:21

12-Aug-02 8:21

Shawn Horton wrote:
Does anyone know of an easy, efficient way to make sure the % sign is printed as well?

I'm not sure what exactly do you want to achieve. You've mentioned that there are fields in data file and vsprintf replaces % sequences with actual values. Do you want to keep a percent sign before the value? If this is the case, try appending %% in front - this will result in one percent sign being printed.

Tomasz Sowinski -- http://www.shooltz.com

What is "scratch" and why can everything be made from it?

Shawn Horton12-Aug-02 8:39

12-Aug-02 8:39

Maybe this will help:

char data_name[DATANAMELEN];

read_function(data_name);

//data_name now contains the value "%recovered"

printf("we read in %s", data_name);

The printf statement to the Richedit window is now
we read in recovered

notice the missing %?

Maybe that is a bit clearer.

My hope is that I will not have to look for a % in character in each variable, and then insert a % in front of that.

Thanks for the help.

Tomasz Sowinski12-Aug-02 8:54

12-Aug-02 8:54

Shawn Horton wrote:
Maybe that is a bit clearer.

Totally clear now. I don't know about any format modifier which could cause [v]sprintf to literally copy % sign.

Tomasz Sowinski -- http://www.shooltz.com

What is "scratch" and why can everything be made from it?

Shawn Horton12-Aug-02 9:01

12-Aug-02 9:01

I should just post something like "Duh I am having a problem" on my first post, because the second one usually makes more sense.

Tomasz Sowinski12-Aug-02 9:09

12-Aug-02 9:09

If you're using MFC in your project, use CString::Format - it will work for you.

Tomasz Sowinski -- http://www.shooltz.com

What is "scratch" and why can everything be made from it?

Daniel Lohmann12-Aug-02 10:34

12-Aug-02 10:34

Sounds like a bug in vsprintf Frown | :-(

It surely should take everything that is passed literally as literals.

Or I am missing something here?

Maybe it is a feature, called somewhat like "recursive format substitution"...
What happens if you replace "%" with "%%" in your data_name?

--

Daniel Lohmann

http://www.losoft.de
(Hey, this page is worth looking! You can find some free and handy NT tools there Big Grin | :-D

)

Shawn Horton12-Aug-02 10:49

12-Aug-02 10:49

Actually, it was a bug in our re-defined printf. The function for the richedit control that we were using was expecting both a format specifier and a va_list, but we forgot the format specifier. Thus, when the function saw
%recovered, it saw an invalid format specifier (%r) and threw out the % like it said it would.

I hate when compilers do what you tell them to do instead of doing what you want them to do.

Thanks for the help.

Shawn

Daniel Lohmann12-Aug-02 12:28

User breakpoint called from code. Please help!

12-Aug-02 12:28

Shawn Horton wrote:
I hate when compilers do what you tell them to do instead of doing what you want them to do.

Yeah... After 40 years of science, computers are still stupid at all. Tons of work remaining for us developer folks Poke tongue | ;-P

--

Daniel Lohmann

http://www.losoft.de
(Hey, this page is worth looking! You can find some free and handy NT tools there Big Grin | :-D

)

redeemer12-Aug-02 6:57

12-Aug-02 6:57

I get this error when using acmDriverEnum to enumerate all the different codecs on my system, this is the callback function:

BOOL WINAPI listCallback(HACMDRIVERID hadid, DWORD dwInstance, DWORD fdwSupport)
{
	if (fdwSupport & ACMDRIVERDETAILS_SUPPORTF_CODEC)
	{
		ACMDRIVERDETAILS details;

		details.cbStruct = sizeof(details);

		acmDriverDetails(hadid, &details, NULL);

		SendMessage(GetDlgItem(ghWnd, IDC_CODECS), LB_INSERTSTRING, 0, (LPARAM)details.szLongName);
	}

	return true;
}

In this routine i simply check if the current driver is a codec, and if it is i add the name of it to a listbox. The error happens when i have looped though all of the different codecs and the return true; statement has been executed. After that it jumps to some assembly code, and this is the stament it gives me the message after completing:

call        dword ptr [ebp+8]

When that statement has been executed, the "User breakpoint called from code at 0x77f9f9df" message appears, and it jumps to this statement:

int         3

I've never experienced this message before and i haven't got a clue what it means.

All help appreciated.

-Rune Svendsen

Daniel Turini12-Aug-02 7:25

Daniel Turini

12-Aug-02 7:25

This is an exception being thrown... Try review the call stack and get some other clues...

Concussus surgo.
When struck I rise.

redeemer12-Aug-02 7:34

12-Aug-02 7:34

Sorry for my ignorance, but what is the call stack and how to i review it?

Thanks.

Daniel Turini12-Aug-02 8:28

Daniel Turini

12-Aug-02 8:28

Try View/Debug Windows/Call Stack (or press Alt+7)

It's a debug window that shows all the functions called until your program got into that line the debugger is showing.

Concussus surgo.
When struck I rise.

redeemer12-Aug-02 9:47

12-Aug-02 9:47

umm, not sure if it makes much sense, but this is the contens of it when the message appears:

NTDLL! 77f9f9df()
NTDLL! 77fb4966()
NTDLL! 77fb3bdc()
NTDLL! 77fa7131()
NTDLL! 77fca4cb()
MSMS001! 01ac7b68()
MSMS001! 01ac7539()
MSMS001! 01abfcf7()
VCT3216! 01254326()

Daniel Lohmann12-Aug-02 7:59

12-Aug-02 7:59

The message "User breakpoint called from code at 0x77f9f9df" means that a software interrupt 3 was thrown, which is used for breakpoints. An int 3 asm instruction is a so called "hardcoded breakpoint" and causes the message and halts the program in the debugger. In debug mode the compiler initializes any unused memory and also some bytes before and after every function with this instruction. This is a good thing, because it let you find jumps to invalid adresses, and obviously such an illegal jump is also your problem.

Okay, so much about the magic things in the background. What actually happens in your case is a bit difficult to figure out. I assume that the stack is not layed out as it should, therefore the app crashes while executing the return statement. Note: The return statement is only the position it crashes - the real problem is somewhere else and just not detected before.

Please do the following:

What happens if you remove anything from your function, but the return true statement? Is the problem still there?
Please show us the line you where you pass the callback function to acmDriverEnum(). Are you doing some ugly cast's there because otherwise it would not compile? Maybe your callback functions prototype is not layed out as it should. Casting it to the "correct type" is a typical source for big trouble, if you are not absolutely sure about what you are doing.

(I really do have a feeling that it is 2. that causes your problem - but hey, it's just a feeling Roll eyes | :rolleyes:

)

--

Daniel Lohmann

http://www.losoft.de
(Hey, this page is worth looking! You can find some free and handy NT tools there Big Grin | :-D

)

redeemer12-Aug-02 9:42

12-Aug-02 9:42

1. I have tried removing everything from the callback function except return true;, and when i do that the messagebox doesn't appear, but in the Debug fan (the one where there's Build, Debug, Find In Files 1 etc.) it says

First-chance exception in MP3.exe (MSACM32.DLL): 0xC0000005: Access Violation.
First-chance exception in MP3.exe (MSACM32.DLL): 0xC0000005: Access Violation.

(yes, the statement is shown twice)

2. The line where i call the function that uses the callback function is as follows:

acmDriverEnum(listCallback, NULL, ACM_DRIVERENUMF_DISABLED);

The prototype of the callback is:

BOOL WINAPI listCallback (HACMDRIVERID hadid, DWORD dwInstance, DWORD fdwSupport);

but that is actually not the original callback function definition, it's like this:

BOOL ACMDRIVERENUMCB acmDriverEnumCallback(HACMDRIVERID hadid, DWORD dwInstance, DWORD fdwSupport);

the reason i changed it was that it wouldn't compile when i used ACMDRIVERENUMCB, a lot of compile errors showed. so i asked what could be wrong and one said that maby ACMDRIVERENUMCB was just a typedef of WINAPI so i used that, could that be where the problem lies?

Thanks for your help.

Daniel Lohmann12-Aug-02 10:29

How to get text of a button when ...

12-Aug-02 10:29

redeemer wrote:
the reason i changed it was that it wouldn't compile when i used ACMDRIVERENUMCB, a lot of compile errors showed. so i asked what could be wrong and one said that maby ACMDRIVERENUMCB was just a typedef of WINAPI so i used that, could that be where the problem lies?

I doubt it. (Maybe this is just because it was me who suggested you to change it Poke tongue | ;-P

. However, I never said is a typdef for WINAPI, but it is a typedef for the pointer to listCallback. Take a look at the definition of ACMDRIVERENUMCB in the header file. The docs are just wrong here.)

However, back to your problem: It works if you remove all code from your listCallback. Therefore it is probable (but not sure...) that the problem is caused by that code. (The exception messages you get are no problem. If the debugger does not claim about an unhandled exception they are catched inside MSACM32.DLL - nothing you should worry about.)

Next step: Trackle it down. If it fails because of that code, check which part of the code (especially the calls to acmDriverDetails() and/or SendMessage()) causes the problem. (Don't forget to pass a valid string in SendMessage() if you remove the call to acmDriverDetails()!)

--

Daniel Lohmann

http://www.losoft.de
(Hey, this page is worth looking! You can find some free and handy NT tools there Big Grin | :-D

)

User 665812-Aug-02 6:53

User 6658

12-Aug-02 6:53

Hi!

I want to get the text of a button from another app.
Usually I use SendMessage with WM_GETTEXT to get the text. But this time it doesn't work because the button has a bitmap AND a caption.
Even Spy++ can't get the text of the button.

It seems like the caption is being drawn at runtime onto the button Frown | :(

Does anyone know a solution?

thanks in advance

modified 12-Sep-18 21:01pm.

Re: How to get text of a button when ...

Tomasz Sowinski12-Aug-02 7:25