using _ultoa_s is creating a problem

[VCProgrammer]

Hi all, I am using _ultoa_s for conversion of long to string using this way

_ultoa_s ( pDir32->Dir [ i ].fileSize,(char *)Name,sizeof(&Name), 10 );
pListCtrl->SetItemText ( index, 2, (char *)Name);

But the problem is sometimes its executing fine but sometimes it just crashes my application.... i am working in vc 2008.. Thanks in advance

[L Madhavan]

sizeof(&Name) is the culprit - the size of an address (pointer) is always 4 bytes. (for a 32-bit compiler) What type is the variable Name? If its a character array, you should use sizeof(Name). if it's a pointer, you need to know the size with which it was allocated.

[Naveen]

VCProgrammer wrote:

But the problem is sometimes its executing fine but sometimes it just crashes my application....

I dont think this is an issue of _ultoa_s. It can also be an issue in accessing pDir32->Dir [ i ].fileSize variable. So first try to isolate it. Please change the code as follows and find out at which line the crash occurs.

unsigned long lFileSize = pDir32->Dir [ i ].fileSize;
_ultoa_s ( lFileSize ,(char *)Name,sizeof(&Name), 10 );

nave [OpenedFileFinder] [My Blog]

[Malli_S]

What is the type of Name ? May be sizeof(&Name) giving the problem.

-Malli...! :rose:****

[Naveen]

L. Madhavan wrote:

sizeof(&Name) is the culprit

:doh: I missed that point. How ever if the Name is allocated in the stack, there is no problem in using sizeof(Name).

nave [OpenedFileFinder] [My Blog]

modified on Wednesday, December 17, 2008 2:34 AM

[Malli_S]

But if Name is dynamically allocated on heap, sizeof(Name) and sizeof(&Name) both returns the size of pointer. Doesn't it ?

-Malli...! :rose:****

[Cedric Moonen]

If Name is a plain string, use strlen instead. It is much safer. Note to self: take a morning coffee before answering questions... :sigh:

Cédric Moonen Software developer
Charting control [v1.5] OpenGL game tutorial in C++

modified on Wednesday, December 17, 2008 3:17 AM

[Naveen]

Malli_S wrote:

Doesn't it ?

Yes :)

nave [OpenedFileFinder] [My Blog]

[L Madhavan]

strlen returns the current length of the string, not the actual size of the buffer. Moreover, if the buffer is uninitialized, (i.e. no null terminator) the behaviour of strlen is undefined.

[Cedric Moonen]

Oh crap, I forgot to take my coffee this morning X| Yes, of course, we need to pass the size of the available buffer, not the size of the string...

Cédric Moonen Software developer
Charting control [v1.5] OpenGL game tutorial in C++