CS Week 6- Pointer and Memory Management

Question 1

new

Answer 1

allocates memory for the given type and returns a pointer to the allocated memory

Question 2

look at notes and lab notes for the coding stuff

Answer 2

:)

Question 3

different ways to use new

Answer 3

1. just one object
   int* point = new int;

2.one object with a specific value
int* point = new int(10);

3. a class
   int* point = new Class;
4. a class with its specific values
   int* point = new Class(77,88);
5. an array of objects
   int* point = new int[10];
6. an array of classes
   int* point = new Class[10];

Question 4

member access operator

Answer 4

->
allows the pointer to access member function
new only one class
not an array of classes

Question 5

delete

Answer 5

deallocates (or frees) a block of memory that was allocated with the new operator
After delete, no attempt to dereference because the value does not exist anymore

Question 6

when to use delete and delete[]

Answer 6

delete when there is only one thing/object allocated

delete[] when there is an array of objects

Question 7

code

Answer 7

region where the program instructions are stored

Question 8

Static memory-

Answer 8

region where global variables (variables declared outside any function) as well as static local variables (variables declared inside functions starting with “static”) are allocated.
-Static variables are allocated once and stay in the same memory location for the duration of a program’s execution

Question 9

the stack

Answer 9

region where a function’s local variables are allocated during a function call
-A function calls adds them (to the top of the stack) and a return removes them
-Think of the picture tyler drew with the stack and how function call are on top of main and return a value down and cannot be access again until another call
-Also called automatic memory - this memory is automatically allocated and unallocated

Question 10

the heap

Answer 10

region where the “new” operator allocates memory and where “delete” operator deallocates memory
Also called free store

Question 11

memory leak

Answer 11

occurs when a program that allocates memory loses the ability to access the allocated memory, typically due to failure to properly destroy/free dynamically allocated memory

free stuff that is no longer used with delete or delete[]
free stuff as private pointers (sub-object) with delete or delete[] in deconstructors

Question 12

garbage collection

Answer 12

automatic process of fencing and freeing unreachable allocated memory locations

Question 13

inline member function

Answer 13

a member function’s definition may appear within the class definition
Use to yield more compact code, keeping longer definitions outside the class

except with declaring variables before use

Question 14

Constructor initializer list

Answer 14

an alternative approach for initializing data member in constructor, coming after a colon and consisting of a comma-separated list of variableName(initValue) items
-Have them in the order they were declared in class definition
-Avoid creating and then modifying, all one step

Question 15

Standard template library (STL)

Answer 15

defines classes for common Abstract Data Types(ADT)

Question 16

vector

Answer 16

is an ADT of an ordered, indexable list of items
The vector ADT is implemented as a class

Question 17

at, size, empty, clear, insert, erase

Answer 17

.at(n) - returns the value at the index n

.size() - returns the size

.empty() - returns 1 or T if size ==0

.clear() - vector still exists but its values do not

.insert(name.begin() + n, m) - takes in position argument indicating where m should be inserted

.erase(name.begin() + n) - takes in a position argument where it should be deleted

Question 18

inserting elements in sorted order

Answer 18

Common use of insert() is to insert a new item in sorted order

1. 1st number is added to the vector
2. If the next number is greater than the 1st, it is added to the end of the vector
3. If the next number is less than both the previous one, it is added to the front of the vector
4. Find the 1st number it is less than
5. And so on