delete vs delete operators in C

Question

What is the difference between delete and delete   operators in C

User · Answer

delete is used for one single pointer and delete   is used for deleting an array through a pointer  This might help you to understand better

User · Answer

This the basic usage of allocate DE-allocate pattern in c    malloc free  new delete  new   delete    We need to use them correspondingly  But I would like to add this particular understanding for the difference between delete and delete    1  delete is used to de-allocate memory allocated for single object  2  delete   is used to de-allocate memory allocated for array of objects  class ABC    ABC  ptr   new ABC 100    when we say new ABC 100   compiler can get the information about how many objects that needs to be allocated here it is 100  and will call the constructor for each of the objects created  but correspondingly if we simply use delete ptr for this case  compiler will not know how many objects that ptr is pointing to and will end up calling of destructor and deleting memory for only 1 object leaving the invocation of destructors and deallocation of remaining 99 objects   Hence there will be a memory leak   so we need to use delete    ptr in this case

User · Answer

When I asked this question  my real question was   is there a difference between the two   Doesn t the runtime have to keep information about the array size  and so will it not be able to tell which one we mean    This question does not appear in  related questions   so just to help out those like me  here is the answer to that   why do we even need the delete   operator

User · Answer

The operators delete and delete    are used respectively to destroy the objects created with new and new    returning to the allocated memory left available to the compiler s memory manager   Objects created with new must necessarily be destroyed with delete  and that the arrays created with new   should be deleted with delete

User · Answer

The delete operator deallocates memory and calls the destructor for a single object created with new   The delete    operator deallocates memory and calls destructors for an array of objects created with new      Using delete on a pointer returned by new    or delete    on a pointer returned by new results in undefined behavior

User · Answer

The delete   operator is used to delete arrays  The delete operator is used to delete non-array objects  It calls operator delete   and operator delete function respectively to delete the memory that the array or non-array object occupied after  eventually  calling the destructors for the array s elements or the non-array object    The following shows the relations   typedef int array type 1       create and destroy a int 1  array type  a   new array type  delete    a      create and destroy an int int  b   new int  delete b      create and destroy an int 1  int  c   new int 1   delete   c      create and destroy an int 1  2  int   d  2    new int 1  2   delete    d    For the new that creates an array  so  either the new type   or new applied to an array type construct   the Standard looks for an operator new   in the array s element type class or in the global scope  and passes the amount of memory requested  It may request more than N   sizeof ElementType  if it wants  for instance to store the number of elements  so it later when deleting knows how many destructor calls to done   If the class declares an operator new   that additional to the amount of memory accepts another size t  that second parameter will receive the number of elements allocated - it may use this for any purpose it wants  debugging  etc        For the new that creates a non-array object  it will look for an operator new in the element s class or in the global scope  It passes the amount of memory requested  exactly sizeof T  always     For the delete    it looks into the arrays  element class type and calls their destructors  The operator delete   function used is the one in the element type s class  or if there is none then in the global scope    For the delete  if the pointer passed is a base class of the actual object s type  the base class must have a virtual destructor  otherwise  behavior is undefined   If it is not a base class  then the destructor of that class is called  and an operator delete in that class or the global operator delete is used  If a base class was passed  then the actual object type s destructor is called  and the operator delete found in that class is used  or if there is none  a global operator delete is called  If the operator delete in the class has a second parameter of type size t  it will receive the number of elements to deallocate

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