Pointers Flashcards
What do pointers do in C++
They point to a location in memory
What is the ‘&’ character
The reference character; a variable with a leading ‘&’ provides the memory address of that variable
How do you declare a pointer?
With the * character.
ex: int* var or int *var
How do you assign stack memory to a pointer?
int var = 7;
int *point =&var;
How is the * character used to dereference?
When put in front of a pointer, it will provide the value in that memory address.
How do you reassign the value in a pointer?
int *pointer = &var;
*pointer = 13;
Given int pointer ‘pointer’, how do you assign the value in pointer’s memory to variable ‘var’?
int var = *pointer;
How is pointer math performed assuming same pointer type?
The pointers will perform arithmatic in the units of the type.
ex: int *one - int *two = 1, assuming they were declared one after the other.
Given array y, what does *y return?
The memory address of the first index.
What is created with int *a;?
Movable pointer to writable int
What is created with const int *b;?
Movable pointer to read-only int
What is created with int *const c;?
unmoveable pointer writable int.
What is created with const int *const d;?
unmovable pointer to read-only int.
What is created with int &e = …;?
read/write reference int
What is created with const int &f = …;?
read only reference
How do you use allocated memory with a pointer?
With the ‘new’ keyword.
What are the 2 keyword pairs to remember for heap memory allocation?
new/delete and new[]/delete[]
What type of memory is on the heap?
Dynamic Memory
How do you get access to the typeid function?
#include <typeinfo>
What does typeid return?
A type_info object.
What is useful about type_info objects?
They are comparable.
What is the “this” keyword?
A pointer to an objects self.
How do you interact with data inside a “this” pointer?
With the ‘->’ operator.
Where should dynamic length array int[x] be allocated?
The heap.
Where should fixed length array int[7] be allocated?
The stack.
What does the ‘sizeof’ operator return?
The byte length of a variable / datatype.
Given int array ‘arr’, how do you get the length of the array?
sizeof(arr) / sizeof(arr[0])
Given ‘int arr[10];’, what does ‘sizeof(arr);’ return?
40
What is the difference between new/delete and malloc/free?
new/delete will allocate / deallocate memory as well as the object to put in that memory, malloc/free only deal with the memory and not the object.
How is memory cleared on the stack vs the heap?
Memory will only clear up on the stack when it falls out of scope, heap memory can be allocated, deallocated, and re-used at will.
