Thread: Class + Memory issues

I have this class, with 3 char-arrays that are initialized like this:

Code:

this->name = (char*) malloc(64);
this->type = (char*) malloc(64);
this->item_class = (char*) malloc(64);

After that, I have a constructor, that copies values to these from a file (read until \n), which ALWAYS work perfectly. I am 100% sure this function is not wrong, since it has worked before, and I haven't changed it. This function copies everything to its correct place.

Now. My problem is:

I have a function that enchants a weapon (warhammer in this case), and because of that, appends the enchantments name to the weapons name (this->name).

warhammer <enchantments name>

These enchantment names are less than 20 characters long. And the weapon names are less than 20 characters long aswell.

Example:

I have a warhammer that I enchant, and when it gets some enchants (not all, some enchants work fine) like " of minor striking" or " of minor intellect", somehow my this->item_class gets overwritten and now says ing or lect.
This shouldnt happen, since I have already allocated memory for up to 64 chars.
The only thing the enchant function does, is appends the enchantments name to this->name.
this->item_class remains untouched.

Why does this happen?

I make it a rule to allocate ATLEAST 64 bytes of memory for all strings, and I have nothing in my program that takes up more than 15-20 bytes on its own.
Add enchant and weapon name together and you still only get at most a 40-byte string.

P.S. this->item_class contains a small string, such as exotic, two-handed or ranged.
I use strcat to append the enchantments name.

It is preferred that std::strings be used in place of raw char * they are much easier to work with and such. But if you want to do things the old way you could at least use new C++ memory allocation(yes it was a pun). Basically instead of calling malloc and free you use new and delete. Example:

Code:

this->name = new char[64];
//do stuff with the name
delete [] this->name;

It is a lot cleaner because you don't have to cast the void* that malloc returns and it is more conventional C++ practices.
As a side note if you allocate with new[], deallocate with delete[] and if you use new, deallocate with delete.

Yes the operators are meant to be paired together so allocate with new, deallocate with delete, allocate with new[], deallocate with delete[].

Originally Posted by brewbuck

Uh, you don't have to cast the return value of malloc(). Or any void *, for that matter. If the compiler complains when you do not cast, it means you forgot to include stdlib.h

If you are talking about C then you are correct. But in C++ you need to cast the void to something because of the increased type saftey in C++.
I don't have a GCC compiler here at work but I do have Visual C++ 2005 which says to me this when I do this

Code:

	void *ptr = new int[10];
	
	int *intPtr = ptr;

Error 1 error C2440: 'initializing' : cannot convert from 'void *' to 'int *' c:\documents and settings\bjohn\my documents\visual studio 2005\projects\temp\temp\temp.cpp 11

Now if I cast it with static_cast<> it loves me agian.

Code:

	void *ptr = new int[10];
	
	int *intPtr = static_cast<int*>(ptr);

Output from GCC:

Code:

void.cpp:2: error: invalid conversion from `void*' to `int*'