C and C++ don't mandate automatic garbage collection, but it's available anyway (e.g., see the Boehm/Demers/Weiser collector). In C++, this can be done automatically in the destructor, making the class easier and less error-prone to use.įalse. This means that, if the object manages a resource (such as a lock, or a database connection) that needs to be released after use, then it is up to the user of the object to manually release it. In Java, once an object is discarded, you do not know exactly when (or even if) the garbage collector will remove it. In none of these cases do you need to manually delete the object that is only necessary when dealing with raw object pointers which, in my opinion, should only be done when absolutely necessary.Ĭ++ also has an advantage over Java here: destruction is always deterministic (that is, you know exactly when it happens). deleting the object if there are no other shared pointers to it. Register(o) // ownership is shared our pointer is still valid deleting the object if it still owns it. The pointer is automatically destroyed after each iteration, Register(o) // ownership may be transferred our pointer is now null in that case In something like your example, you would use automatic storage: for (int i = 0 i const & o) The standard library comes with two smart pointers: auto_ptr and smart_ptr (the latter is reference-counting, but some old compiler may not support it).Ĭ++ certainly does have automatic storage duration it just has other types of storage duration as well, and the ability to choose what is most appropriate. More advanced version of smart pointers can implement reference counting (so the pointed object will be released only when all smart pointers referencing it go out of scope) and even garbage collection. regular) pointer, and deletes the pointer when its destructor gets called. A smart pointer is an object allocated on the stack, that wraps a 'dumb' (i.e. In that case, you can use pointers directly, but if you don't want to deal with manually deleting pointers and all the problems it can lead to, you'd usually use a smart pointer. you need to create an object and store a reference to it that stays alive when you leave the function that created the object). Practically speaking, when programming in C++ you'd usually put local variables on the stack (and get all the advantages of RAII without lifting a finger), unless you need to keep them alive for longer than that (e.g. One of them is smart pointers, that allow dynamically allocated objects to be freed automatically just like their stack counterparts, and you can use sophisticated smart pointers to implement your own version of garbage collection if you want.Īnother advantage of RAII is that finally-blocks are rarely necessary in C++: local variables that reference to a resource that should be freed immediately are usually allocated on the stack, and therefore get released automatically. This behavior of C++ stack values (automatic destruction when they go out of scope), which is awkwardly termed RAII (Resource Acquisition Is Initialization) allows for very nice things that Java just can't do. will get called, but the object's stack memory will be reused. case (a loop), the compiler will optimize things, so object's destructor Object gets automatically deallocated, or more accurately, in this specific Object o = Object() // Note we're not using the new keyword here. If you allocated your object on the stack however, it always gets automatically released when it goes out of scope, and you don't have to wait for garbage collection to happen - it's always released immediately: for(int i = 0 i < 100 i++) Release object memory (and call object destructor, if there is one) The most basic way to that would be to free your object reference (or pointer, since this is C++) manually when you don't need it anymore: for(int i = 0 i < 100 i++) from Wikipedia:Ĭ++ doesn't have (built-in) garbage collection, but that doesn't mean you should let your dynamically allocated memory stay allocated forever. Do we have to reboot each time as well to properly remove the Object reference in C++?įor those who say that there are no problems deleting an object more than once in C++. In C/C++ we have to manually remove the Object address inside the for loop. Rough Example: for(int i = 0 i < 100 i++) In Java, because there is Automatic Garbage collection, after a single loop is executed the address of the object is removed each time automatically. I have a for loop running for 100 times inside which this single object is created every time the loop is run. There is no Automatic Garbage Collection in C/C++.Īssume that I wrote a simple program in C/C++ and created a single object.Īssume that there are exactly 10 or extremely limited number of addresses for allocation.
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