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Member 10964099 wrote: why is this happening ?
It append because it designed this way. That is how pointers work.
I recommend to read THE book "the C Language" from Kernigan & Ritchie.
The C Programming Language - Wikipedia, the free encyclopedia[^]
Patrice
“Everything should be made as simple as possible, but no simpler.” Albert Einstein
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Because s is a pointer.
char * s =(char*)malloc(10);
s="test"
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What all the others said and more generally rarely if ever do use an equal sign on a string in C at any other time than creation.
There are functions required to add, copy, compare, split and search strings and you can't just use mathematical symbols like "=" and "+" to do things with strings like you can in some higher languages. Strings are not mathematical types and you can't use mathematical functions to do things with them.
Those coming from a coding background in Java or Basic tend to do what you did and you have to unlearn it when using C because "string1" + "string2" will not work either, you will need to use strcat functions. String compares are likewise a function and you can't use mathematical equality signs to compare two strings.
Learning the string functions, it is a requirement of learning the C language.
In vino veritas
modified 14-May-16 12:10pm.
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inside a C function I have this code
printf("%s",final);
I do a fork and this is part of the childs code
the final string is not printed when the execl line is not commented out,nor are any printf calls before it
why is this happening ?
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Without seeing more code it is anyone's guess.
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Probably due to line buffering.
Try
printf("%s\n", final); or add
fflush(stdout); before the execl() call;
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If your on Eclipse it is a known bug (id=173732)
The fflush(stdout); fix is the only way around it as horrible as it is.
In vino veritas
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Windows 7 UAC prevents my application to write log data in the installation folder. The original text log file exists from the very beggining, but its empty.
When I start my app with the -L parameter to start logging, it does not write anything due the UAC control. If I rum my app with Admin Priviledges then it works.
As you can understand I can not suggest my client to run the app with right click and "run as an Administrator".
Is there any solution for that ?
Best Regards,
sdancer75
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Yes - don't try to write files in the installation folder. Your application will not have permission to do so.
Instead, create a folder for your application under one of the AppData locations - CSIDL_APPDATA, CSIDL_LOCAL_APPDATA or CSIDL_COMMON_APPDATA - and write the log files to that folder.
CSIDL (Windows)[^]
SHGetFolderPath function (Windows)[^]
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thank you
Is that backward compatible with windows xp/vista ?
I think that win Xp does not support AppData. Is that correct ? What to do in this case ? Check the os and take a path decision specifically for it ?
sdancer75
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It should be supported in XP - the folder was called "Application Data" / "Local Data" back then.
They changed it to "AppData\Roaming" and "AppData\Local" in Vista to reduce the chances of code breaking the 260-character path limit. Similarly, the "Documents and Settings" folder was renamed to "Users".
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Thank you for your help 
Best Regards,
sdancer75
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This break in CWnd::WindowProc randomly appears when running my application(originally released in 2010 and runs 24/7 in many places) in debug. In release mode it crashes.
The message type is always 874(x36A).
The only true call backs I have are for custom draw list boxes and typically when I have an error in those routines MFC catches and breaks at that point. Obviously that are countless other messages processed.
I am trying to determine A: what is message 874? and B: what circumstances cause it to be posted (though A may answer B)?
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I cannot find the specific message number in Winuser.h in VS 2013, but I did find the following two lines:
#define WM_AFXFIRST 0x0360
#define WM_AFXLAST 0x037F
Googling for WM_AFXFIRST came up with: WM_AFXFIRST - Google Search[^].
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Thanks - I found those two - Jochen below narrowed it down.
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Message 0x036A is WM_KICKIDLE (defined in afxpriv.h). It is a private MFC message used to update the UI (e.g. menu items, tool bar buttons and the status bar).
So you might check your UI update handlers if one of those is the error source.
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Thanks - I must have been too tired to figure that one out.
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Austin Donaghy wrote: This break in CWnd::WindowProc randomly appears when running my application(originally released in 2010 and runs 24/7 in many places) in debug. In release mode it crashes.
There is a good essay of Joe Newcomer: Debug vs. Release[^]
I'd recommend to check it out!
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99% of the time if you get a difference between release and debug mode you forgot to zero a variable and assume it is.
Turn the warning levels up to full and you should get a warning saying "use of uninitialized variable".
Usually it is something like this
int Bad (int someval){
int i;
if (someval > 0){
i = 1;
}
if (i == 0) return (1);
return (0);
}
In debug mode all local variables are zeroed automatically. That simply doesn't happen in release mode the variables will start at whatever rubbish was in the stack at the position it was allocated.
In the above code the behaviour of "bad" is totally predictable in debug mode as "i" will always start at 0. In release mode you have no idea what is going to happen as "i" could start at any value and the return is purely chance based.
Look carefully at the code, now try compiling it and tell me if you get a warning
In vino veritas
modified 8-May-16 9:48am.
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hi i m quite newbie at computer programming and i need more detailed information about classes at c++.is there any good detailed book about classes at c++
modified 6-May-16 7:17am.
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I have a question about the Computational Geometry, C++ and Wykobi which is found at the link below.
Computational Geometry, C++ and Wykobi[^]
The code available with this article has a VCL graphics file named 'wykobi_graphics_vcl.hpp' for use with the IDE C++Builder from Embarcadero Technology. Are there any instructions to compile these files into a C++Builder project? Some of the files are the VC file type .inl which I am not sure how to handle.
Thanks.
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Please use the forum at the end of the article, so the writer of the article (and code) can help.
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