int* ptr1 = NULL;
int* ptr2 = NULL;
ptr1 = new int(5);
ptr2 = ptr1; // both pointer points to the same memory location
delete ptr2; // delete
// is there any function like this one???
if( test_pointer( ptr1 ) {
*ptr1 = 6;
}
Test if a pointer is still valid (C++)
Author
I wonder, is there a way to test if a pointer is still pointing to a valid adress in memory, something like:
You should always make the deleted pointer point to NULL (0). Then you can check it like this.
if(ptr != NULL)
..
if(ptr != NULL)
..
there is but i'm not sure the exact functions.
also you could just do this:
also you could just do this:
bool testPointer (void* test) { if (test) return true; return false;}//orif (test) { // where test is a pointer return true;
If you are coding for Windows, then you can use IsBadReadPtr(); and IsBadWritePtr(); functions.
IsBadWritePtr
IsBadReadPtr
Hope this helps.
IsBadWritePtr
IsBadReadPtr
Hope this helps.
No, there's not. At least, not easily.
Look into boost's shared pointers. I've never used them, but I hear good things.
CM
Look into boost's shared pointers. I've never used them, but I hear good things.
CM
IsBadWritePtr
IsBadReadPtr
are ok but even Microsoft doesn't recomend them as they're not thread safe.
Gennerally this is done by wrapping a try/catch block around you trying to access the pointer. If an exception is thrown then its invalid.
However, the pointer could point ot valid memory but still be invalid for yoru purposes, which is another reason that the IsBadRad/WritePtr methods are basically worthless. Don't use them in any serious code.
Cheers
Chris
Alternatively, if you need to let everyone who has the pointer know that it is gone, you could use a double pointer.
Quote:Original post by Pipo DeClown
You should always make the deleted pointer point to NULL (0). Then you can check it like this.
if(ptr != NULL)
..
I think you've missed the point. What if you have two pointers pointing to the same thing and you use one of them to delete it and set that pointer to null? The other pointer won't have a clue what has just happened.
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