Archive for the ‘programming’ Category

Fix: Breakpoints in wrong lines (=offset) in Visual Studio 2012

Friday, December 11th, 2015

Just had a very weird issue in VS2012 which cost me about an hour, so maybe this helps others.

When I placed breakpoints in a certain file, they more in fact displayed one line *below*. Sometimes even in blank lines. And often they didn’t work. This happened only in one file and only after a certain function. I tried a lot of things regarding the function, but that didn’t help.

It turned out that somehow the newlines codes for wrong here. If you look at the file in a hex editor, newline codes are normally:

At the problem location it was only:

And that seemed to cause headaches to VS. Copying the entire text into an alternative editor and then back again fixed the file.

Posting requesting multiple products with inAppPurchaseManager

Monday, August 26th, 2013

Documentation for inAppPurchaseManager is poor at best. Here’s how to initialize with multiple products:
window.plugins.inAppPurchaseManager.requestProductsData([“myproduct1”, “myproduct2”, “myproduct3”], function(feedback)
for (var c=0; c<feedback[0].length; c++)
console.log(“Succeded: “+feedback[0][c][‘id’]);

for (var c=0; c<feedback[1].length; c++)
console.log(“Failed: “+feedback[1][c]);

inAppPurchaseManager and config.xml

Monday, August 26th, 2013

Just a short note because I found it nowhere else on the net:

If you’re getting this error:
ERROR: Plugin ‘InAppPurchaseManager’ not found, or is not a CDVPlugin. Check your plugin mapping in config.xml.

You’ll need these magic words to integrate inAppPurchaseManager into your config.xml:
<feature name=”inAppPurchaseManager”>
<param name=”ios-package” value=”InAppPurchaseManager”/>

Storing crash relevant information

Saturday, June 22nd, 2013

Sometimes it’s helpful to store debug information on a regular basis somewhere and recover it if the program is crashed and restarted to get info about the cause of the crash. Unfortunately, there’s no perfect way for storing this data in Windows. And you don’t want to slow down your program to much. So I tried a benchmark and compared RegSetValueEx against SetFilePos(0) + WriteFile. (In both cases the handle was opened just once then used for writing 100.000 times.

And it turned out that WriteFile is 10x faster. More interesting facts:

– FILE_ATTRIBUTE_TEMPORARY didn’t change a thing.

– My SSD is fast (298ms), but my hard disk is faster (268ms, don’t ask me why) and my Ramdisk faster than both (206ms).

Dangerous MakeLower

Thursday, May 2nd, 2013

Got weird crashes at customers with foreign languages? Microsoft’s MFC’s MakeLower could be the culprit. Seems to be poorly written because it can crash if it doesn’t like the string. I could even reproduce it here by switching the Windows-Locale for non-unicode apps the Japanese and process some strings contains German umlauts. Bottom-line? Don’t use, write your own… 🙁

Weird TextOut Unicode problems

Friday, October 26th, 2012

After porting Easy2Sync for Files to Unicode I experienced some really weird problems with some foreign characters. Unicode in general worked, Japanese characters were displayed nicely (not that I could read them). But Cyrillic characters failed when printed with TextOut and were displayed as small black rectangles.

Even weirder: Adding just 1 Japanese character to a string with Cyrillic characters caused the entire string to be printed right.

It seems that TextOut is only 50% Unicode compatible (of course Microsoft doesn’t mention this). So one has to use DrawText instead, which doesn’t seem to have these limitations. Since DrawText behaves differently regarding the position and background drawing, here’s a wrapper which fixes this and makes it behave like ExtTextOut:

void FixedExtTextOut (CDC *pDC, int x, int y, UINT nOptions, LPCRECT lpRect, LPCTSTR lpszString, UINT nCount, LPINT lpDxWidths)
 CRect rr(x, y, lpRect->right, lpRect->bottom);

 pDC->FillSolidRect(lpRect, pDC->GetBkColor());
 pDC->DrawText(lpszString, nCount, &rr, 0);

You’re not gonna catch this…

Thursday, June 14th, 2012

You're not gonna catch this... (LIttle League baseball, May 2009 - 03 by Ed Yourdon; CC BY-SA 2.0)

C++ exceptions can be surprising. This works easily:

catch(…) //Catch all

But if you replace “throw(1);” with “throw;”, it suddenly doesn’t work anymore. Code compiles, exception is thrown, but it’s not caught. The program is terminated

Turning off floating point exceptions against crashes

Friday, June 1st, 2012

It sounds quite mad, but either of these lines can crash a program: (C++, Visual Studio 2005)

long x = long(my_float_var);
float f = exp(my_float_var);

If the number is too large/small, the program is terminated. (No, try/catch doesn’t help.) And to make it even stranger, this happens only on some computers. And of course it happened on the customer’s computer and not on mine…

To fix this, it helps to turn off the floating point exceptions:

Of course the problem of the large number still exists, but now the program at least continues to run, and I have a chance to handle it.

EnumResourceNames + RT_STRING

Friday, May 4th, 2012

It sounds pretty straightforward to enumerate the resources  in a file. But it turned out to be rather a lot of work (and waste of time), since the MS doesn’t tell you, that it doesn’t enumerate the strings, but blocks of strings in a binary format that you have to process yourself.

Here’s how to do it:

BOOL CALLBACK EnumResNameProc(HMODULE hModule, LPCTSTR lpszType, LPTSTR lpszName, LONG_PTR lParam)
 switch ((int)lpszType)
 case RT_STRING:

 if (hRes)
 HGLOBAL hGlo = LoadResource(hModule, hRes);
 LPCWSTR lpStr = (LPCWSTR)LockResource(hGlo);
 DWORD dwsize = SizeofResource(hModule, hRes);

 long count=0;
 for (int i=0; i < (int)dwsize; i++)
 if (count>=16)

 if (lpStr[i])
 WORD *pString = lpStr+i+1;
 long lString = lpStr[i];

 //Process string here

 i += lpStr[i];


EnumResourceNames(hModule, RT_STRING, &EnumResNameProc, NULL);

The secret back-to-edit hotkey

Thursday, June 2nd, 2011

Just a tiny trick today.

When you’re programming, you’re often…

  • typing something
  • Then you browse through the same file, look for something
  • copy something
  • And now you want to get back  to the place that you previously edited.

There’s a secret hotkey (actually a sequence) for that which works in most editors: Ctrl+Z, Ctrl+Y.

Works in Visual Studio, Word, text editors, etc.