Raw pointers are used extensively in both C and C++ for three main purposes:
* to allocate new objects on the heap,
* to iterate over elements in arrays or other data structures.
* to pass functions to other functions
Raw pointer features:
* A raw pointer is a pointer whose lifetime isn't controlled by an encapsulating object, such as a smart pointer.
* A raw pointer can be assigned the address of another non-pointer variable, or it can be assigned a value of nullptr. A pointer that hasn't been assigned a value contains random data.
* A pointer can also be dereferenced to retrieve the value of the object that it points at.
* A pointer to void simply points to a raw memory location. Sometimes it's necessary to use void pointers, for example when passing between C++ code and C functions.
* Assigning any pointer type to a void pointer without using a cast is allowed in C or C++. But we can not assign a void pointer to a non-void pointer without using a cast to non-void pointer type in C++.
<b>When should use raw pointers</b>
Raw pointers are the source of many serious programming errors. Therefore, their use is strongly discouraged. Modern C++ provides smart pointers for allocating objects, iterators for traversing data structures, and lambda expressions for passing functions.
Use raw pointer when ownership should not be local.
As an example, a pointer container may not want ownership over the pointers in it to reside in the pointers themselves. If you try to write a linked list with forward unique ptrs, at destruction time you can easily blow the stack.
A vector-like container of owning pointers may be better suited to storing delete operation at the container or subcontainer level, and not at the element level.
In those and similar cases, you wrap ownership like a smart pointer does, but you do it at a higher level. Many data structures (graphs, etc) may have similar issues, where ownership properly resides at a higher point than where the pointers are, and they may not map directly to an existing container concept.