Right way to delete a pointer
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CSocket * sock; is it a right way to delete a pointer sock = NULL; delete sock; Or can I directly do delete sock; Regards.
zahid_ash wrote:
sock = NULL; delete sock;
This won't do anything ! You first have to delete the pointer THEN set it to NULL:
delete sock;
sock = NULL;
Cédric Moonen Software developer
Charting control -
CSocket * sock; is it a right way to delete a pointer sock = NULL; delete sock; Or can I directly do delete sock; Regards.
CSocket* pSocket; // Allocate a memory for pSocket // Delete a allocated memory if(pSocket) { delete pSocket; pSocket = NULL; } Regards Amar.:)
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CSocket* pSocket; // Allocate a memory for pSocket // Delete a allocated memory if(pSocket) { delete pSocket; pSocket = NULL; } Regards Amar.:)
I think you can even skip the checking for
NULL:delete pSocket; // without redundant "if(pSocket != NULL) ..."
pSocket = NULL;This is because
deleteoperator performs itself a test for null pointers. You only have to be sure thatpSockedwas properly initialized before with a right value or withNULL. -- modified at 9:42 Friday 2nd June, 2006 -
CSocket * sock; is it a right way to delete a pointer sock = NULL; delete sock; Or can I directly do delete sock; Regards.
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I think you can even skip the checking for
NULL:delete pSocket; // without redundant "if(pSocket != NULL) ..."
pSocket = NULL;This is because
deleteoperator performs itself a test for null pointers. You only have to be sure thatpSockedwas properly initialized before with a right value or withNULL. -- modified at 9:42 Friday 2nd June, 2006Viorel Bejan wrote:
This is because delete operator performs itself a test for null pointers. You only have to be sure that pSocked was properly initialized before with a right value or with NULL.
This only happens in debug builds. You should ALWAYS check for null before deleting a pointer. Calling delete NULL has undefined behavior and should be avoided. If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac
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Viorel Bejan wrote:
This is because delete operator performs itself a test for null pointers. You only have to be sure that pSocked was properly initialized before with a right value or with NULL.
This only happens in debug builds. You should ALWAYS check for null before deleting a pointer. Calling delete NULL has undefined behavior and should be avoided. If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac
Zac Howland wrote:
This only happens in debug builds. You should ALWAYS check for null before deleting a pointer. Calling delete NULL has undefined behavior and should be avoided.
That's not true, Zac. See 16.8 on http://www.parashift.com/c++-faq-lite/freestore-mgmt.html[^] Regards, Nish
Nish’s thoughts on MFC, C++/CLI and .NET (my blog)
Currently working on C++/CLI in Action for Manning Publications. Also visit the Ultimate Toolbox blog (New) -
Always NULL the pointer after deleting it. Otherwise you could (if you're not very, very careful) try to delete the same pointer twice, which will result in an access violation. Deleting a NULL pointer however is perfectly safe.
Another reason for doing that is that the address used for the recently-deallocated memory may still be valid in your address space and while not technically valid for use, accessing it might not cause an IPF or Access Violation. For example:
TCHAR *pcBuffer = new TCHAR[ 1024 ];
delete [] pcBuffer;
pcBuffer[ 1 ] = _T( 'A' );The above code may not crash even though the pointer is technically invalid. By setting it to
NULL, you just about guarantee that accessing it will cause an Access Violation (at least if on Win32 and if the access range of the pointer is <4096, because that hits the reserved "NULLpointer page" which causes an instant exception, IIRC). Peace! -=- James
If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Avoid driving a vehicle taller than you and remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
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Viorel Bejan wrote:
This is because delete operator performs itself a test for null pointers. You only have to be sure that pSocked was properly initialized before with a right value or with NULL.
This only happens in debug builds. You should ALWAYS check for null before deleting a pointer. Calling delete NULL has undefined behavior and should be avoided. If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac
Zac Howland wrote:
Calling delete NULL has undefined behavior and should be avoided.
Nope,
delete NULLis required by the C++ Standard to do nothing. It is perfectly safe.
My programming blahblahblah blog. If you ever find anything useful here, please let me know to remove it.
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Zac Howland wrote:
This only happens in debug builds. You should ALWAYS check for null before deleting a pointer. Calling delete NULL has undefined behavior and should be avoided.
That's not true, Zac. See 16.8 on http://www.parashift.com/c++-faq-lite/freestore-mgmt.html[^] Regards, Nish
Nish’s thoughts on MFC, C++/CLI and .NET (my blog)
Currently working on C++/CLI in Action for Manning Publications. Also visit the Ultimate Toolbox blog (New)Yes, the standard says that. However, most compilers did not meet that standard until recently (and some still don't). It is one of those better safe than sorry things. If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac
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Yes, the standard says that. However, most compilers did not meet that standard until recently (and some still don't). It is one of those better safe than sorry things. If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac
Zac Howland wrote:
However, most compilers did not meet that standard until recently (and some still don't). It is one of those better safe than sorry things.
Compilers don't meet the Standard mostly in some areas of template handling. Deleting a zero is perfectly safe and has been for quite a while.
My programming blahblahblah blog. If you ever find anything useful here, please let me know to remove it.
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Zac Howland wrote:
However, most compilers did not meet that standard until recently (and some still don't). It is one of those better safe than sorry things.
Compilers don't meet the Standard mostly in some areas of template handling. Deleting a zero is perfectly safe and has been for quite a while.
My programming blahblahblah blog. If you ever find anything useful here, please let me know to remove it.
Nemanja Trifunovic wrote:
Compilers don't meet the Standard mostly in some areas of template handling. Deleting a zero is perfectly safe and has been for quite a while.
Let me put it this way ... There is a reason why the DirectX libraries define the following macro:
#define SAFE_DELETE(p) if(p) { delete p; p = NULL; }If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac -
Nemanja Trifunovic wrote:
Compilers don't meet the Standard mostly in some areas of template handling. Deleting a zero is perfectly safe and has been for quite a while.
Let me put it this way ... There is a reason why the DirectX libraries define the following macro:
#define SAFE_DELETE(p) if(p) { delete p; p = NULL; }If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week ZacZac Howland wrote:
There is a reason why the DirectX libraries define the following macro
Yep, there is: Microsoft DirectX programmers don't know C++ very well. ;P
My programming blahblahblah blog. If you ever find anything useful here, please let me know to remove it.