The difference between new and malloc

（1）new and delete yes C++ Of keyword / Operator ,malloc And free yes c++/c The standard of language function .

（2）malloc need Explicitly specify the allocated memory size ,new Unwanted .

（3）new Operator from Free storage area Upper object Dynamic allocation Memory space , and malloc Function from Pile up Dynamic allocation of memory on .
【 notes 】 Usually through new Operator for memory request , This memory is the free storage area .

（4）new When operator memory allocation succeeds , Return object type , No type conversion required , so new Is in accordance with Type safety Sex operator ;malloc return void*, Need to pass through Cast take void* The pointer is converted to the type we need .

（5）new When the operator memory allocation fails , Throw out bad_alloc abnormal ;malloc Return when memory allocation fails NULL.

（6）new The operator There are constructors and destructors , While opening up space , The constructor of the custom object will be called to complete initialization ;malloc It will only open up space .

（7）malloc After allocating space , Can pass realloc Expand memory ;new Operator cannot expand memory again .

（8）new relative malloc Low efficiency , because new The bottom layer encapsulates malloc.