C++ Deck 7

Question 1

What is a composite variable?

Answer 1

Variables that are capable of storing multiple values under the same name with some way to tell them apart.

Question 2

What is the simplest form of composite data type?

Answer 2

An array

Question 3

What is an array?

Answer 3

Data structures that allow the storage of multiple elements of the same type in contiguous memory locations.

Question 4

What does it mean that an array is indexed?

Answer 4

The elements contained in the array are numbered (starting at 0)

Question 5

True or False: Every element in an array must be the same data type.

Answer 5

True

Question 6

What is the formula for calculating the memory address of an index in an array?

Answer 6

Address = starting address + (size of element type * index number)

Question 7

Which of the following is NOT a property of an array:

a. Same Data Type
b. Continuous in Memory
c. Indexed (Beginning at Zero)
d. Variable size upon declaration

Answer 7

d. Variable size upon declaration

Question 8

What is the index range of an array?

Answer 8

0 to size-1

Question 9

What is the syntax of declaring an array?

Answer 9

typeName variableName[size];

The size in the brackets must be an integer literal or a constant variable. The compiler uses the size to determine how much space to allocate (i.e. how many bytes)

Question 10

True or False: When initializing an array using set notation, it is permissible to exceed the number of values allocated. C++ will adjust the size.

Answer 10

False

Question 11

A c-style string is implemented as an array of type char that ends with what?

Answer 11

The null character

char name[7] = “Connie”;
(note that it’s 6 characters long, but room has been left for the null character to be the 7th index. This is REQUIRED.)

It’s the equivalent of:

char name[7] = {‘C’, ‘o’, ‘n’,’n’,’i’,’e’,’\0’};

Question 12

Is this a valid way to declare and initialize an array:

int list[] = {1, 3, 5, 7, 9};

Answer 12

Yes, C++ will make the array size just large enough to capture the initialized data.

Question 13

Which of these is legal initialization of an array:

int list[5] = {1, 2};

int nums[3] = {1, 2, 3, 4};

Answer 13

int nums[3] = {1, 2, 3, 4}; is illegal because the number of elements being initialized (4) is greater than the size (3).

int list[5] = {1,2}; has fewer elements initialized than the size, but the uninitialized elements are simply defaulted to 0: {1, 2, 0, 0, 0}

Question 14

True or False: You can initialize an array with a for loop, and this is a common way to do so.

Answer 14

True.

int numList[10];

int i;

for (i=0; i < 10; i++)
numList[i] = i*2;

The above loop initializes numList to {0, 2, 4, 6, 8, 10, 12, 14, 16, 18}

Question 15

In this array:

int numList[10];

How would one assign a value of 6 to the 8th element of the array?

Answer 15

numList[7] = 6;

Question 16

True or False: An out of bounds reference to an array is syntactically legal.

Answer 16

True.
However, you shouldn’t do this as it will result in run-time errors.

Question 17

True or False:

int list1 = list2;

This will copy the contents of the array list1 into array list2 if they are the same size.

Answer 17

False.
You must copy array contents element-by-element. This is called a DEEP COPY.
A very simple for loop can accomplish this:

for (int i = 0; i < 5; i++)
list1[i] = list2[i];

Question 18

Is it common to pass the array size explicitly as an additional parameter in a function?

Answer 18

Yes.
The reason is because arrays lose their size information when passed to functions, so having a size parameter in the function helps to make sure the array performs operations accordingly within the function.

You can also use a sentinel value, such as ‘\0’ for character arrays, to mark the end of the array.

Question 19

Does C++ allow direct return of an entire array from a function?

Answer 19

No.
You’ll have to use pointers to do so indirectly (covered later).

Question 20

True or False: It is possible to call functions with array values as parameters.

Answer 20

True.

Question 21

What is the formula for calculating the address of a particular row and column intersection in a 2D matrix array?

Answer 21

address = StartingAddress + ((row_number * number_of_columns) + column_number) * type_size

Question 22

If you try to print out an array using only its name, what will happen?

Answer 22

It will print out the memory address of the starting address of the array (i.e. 0 for a 1D array or 0,0 for a 2D array.)