c++ for java programmers tutorial series quiz

Question 1

dynamic vs static memory allocation

Answer 1

static memory allocation is done at compile time, before program is run..
dynamic memory allocation is done DURING EXECUTION.

Question 2

get the address of variable “item”

Answer 2

&item

Question 3

int *myVar;

Answer 3

declares a pointer called “myVar”;

Question 4

pointer

Answer 4

• stores an address in memory

Question 5

int *p = &x;

Answer 5

sets pointer p to the address of x

Question 6

arrays in c++ differences from java

Question 7

pass by value

Answer 7

pass in a copy of the object (this is the default)

Question 8

pass by reference

Answer 8

pass in a reference–the address the object is at

Question 9

What does this do?
int p* = &cat;
p* = 7;

Answer 9

1. sets pointer p to be the address of cat
2. deferences p, setting the thing at p to 7.
3. now, cat is 7

Question 10

Function prototype

Answer 10

the “signature” of a function placed at the top of a file (to get around the fact that a function has to have “seen” the other function above it in order to reference it

Question 11

If you do NOT initialize a variable, what could happen?
example
int cat;

Answer 11

1. it will assign a pointer for this at some memory location
2. accessing cat will now give you whatever was last written to that location!

Question 12

true/false: c++ will throw an error if you index out of bounds in an array

Answer 12

false! it will allow you to access that

Question 13

an array in java is really just ______

Answer 13

a pointer to the first element in the array.
the ith element of the array is just pointer + size_of_int * i

Question 14

the value of a boolean expression is ___ if true and ___ if false

Answer 14

literally anything other than 0 if true, 0 if false

Question 15

advantages of declaring a number as unsigned

Answer 15

get a larger range of positive values out of it

Question 16

evaluate this.
if (c = 0)

Answer 16

assigns 0 to c, returning 0 -> false always

Question 17

what happens if you do this?
int arr[10] = {1,2};

Answer 17

arr will contain 1, 2,, then 0’s for all the other elements

Question 18

what does this do?
void myMeth(const int myInt&)

Answer 18

method with pass-by ref arg, (you pass in the value, but it takes the ref of it) that won’t allow you to modify it in the function
- that way, you don’t have the expense of copying it, but you don’t have to worry about overwriting it

Question 19

multidim array

Answer 19

int arr[3][2]; // 3x2 array

Question 20

how do c strings work?

Answer 20

read along string, char by char, until null is reached.
if null not reached, it would go on forever?
like other arrays, they are unbounded

Question 21

What does this do?
*(arr + 3) = 7;

Answer 21

look at pos of first element in arr. then look at element 3*int_size) away element address. deref that to get what it is, set the thing at that memory address to 7.

i.e. arr[3] = 7;

Question 22

What does this do?
delete myVar;

Answer 22

mark the position in memory occupied as ok to be allocated again for dynamic allocation with new.

it does NOT set the value there to null, it does not modify the pointer.

if we try to access the pointer and look there in memory, it might give something else that’s weird now.

Question 23

memory leak

Answer 23

when you forget to delete something when you’re done (that memory can’t be used now)

Question 24

dangling pointer

Answer 24

a pointer that points at something that has been freed/deleted

Question 25

If a method can be overridden, it must be marked as ___.

Answer 25

Virtual