Cit 120 Ch. 7

Front 1

What do arrays allow you to do?

Back 1

store and work with a group values of the same data type. creates consecutive space in memory

Front 2

How do you define an array?

Back 2

int days[6];

data type name [size declarator];

size declarator indicates the number of elements the array can hold

Front 3

What are the guidelines for choosing the size declarator of an array?

Back 3

must be a constant integer expression with a value greater than zero. can be an integer literal or an integer named constant

starts at 0.

6 elements: element 0, element 1, element 2, element 3, element 4, element 5

Front 4

How do you calculate the size/memory requirements of an array?

Back 4

multiply the size of the individual elements by the number of elements in the array

Front 5

The individual elements of an array are assigned unique ________ that are used to access the elements

Back 5

subscripts

Front 6

How do you assign the first element of the array hours to 20?

Back 6

hours[0]=20;

read, "hours sub zero is assigned twenty"

Front 7

Do local arrays have default initialization values? What about global arrays?

Back 7

local: no default

global: default to 0

Front 8

What is the difference between the array size declarator and subscript?

Back 8

[#] in definition: size declarator
[#] of assignment statement or any statement that works with the array: subscript

size declarator: int days[6]; // defines an array with 6 elements
subscript: days[5] = 20; // sets the 6th element to 20
cout << days[2]; // displays 3rd element of days

Front 9

The size declarator of an array definition must be a _________ or _______. The subscript may be a ____________.

Back 9

declarator: literal or constant

subscript: variable --> can use loops to cycle through arrays

Front 10

Can any integer expression be used as an array subscript?

Back 10

yes

cin >> hours[count-1]; // valid expression

Front 11

How do you need to input and output elements of an array?

Back 11

one at a time. Cannot just display or fill the whole array at once

Front 12

How do you read data from a file into an array?

Back 12

open the file and use a loop to read each item from the file, storing each item in an array element. loop should iterate until the array is filled or the end of the file is reached

while (count < ARRAY_SIZE && inputFile >> numbers[count])

count++;

inputFile >> numbers[count]; <-- It actually does this action and then tests the "truth" of whether it was able to

Front 13

How do you write the contents of an array to a file?

Back 13

use a loop to step through each element of the array, writing its contents to a file

for (count=0; countoutputFile << numbers[count]=count << endl;

saves 0-9 in the file

Front 14

Does C++ prevent you from overwriting an array's bounds?

Back 14

no

Front 15

What is a common mistake when working with arrays?

Back 15

off-by-one error

easy to make because subscripts start at 0, not 1

Front 16

How do you initialize an array?

Back 16

put the initialization list inside braces and separate elements with commas

int days[7] = {7, 6, 5, 4, 3, 2, 1};

or

int days[7]={7,6,

5,

4,3,2,1} // can spread initialization list across multiple lines

Front 17

How can you force C++ to display the ASCII value of characters stored in an array named letters?

Back 17

cout << static_cast(letters[count]);

Front 18

How do you partially initialize an array? What happens to the uninitialized elements?

Back 18

assign values to the first n elements of the array

the rest of the uninitialized elements are set to 0

Front 19

Does C++ provide a way to skip elements in the initialization list?

Back 19

No. If you leave an element uninitialized, all elements that follow it must be uninitialized

Front 20

What is implicit array sizing?

Back 20

Defining an array without directly specifying the size. you must provide an initialization list

int num[]={1,2,3,4}

C++ will count the number of elements in the initialization list

Front 21

What is a range-based for loop?

Back 21

loop that automatically iterates once for each element in an array. Each time the loop iterates, it copies an element from the array to a variable

Front 22

What are the benefits of using a range-based for-loop?

Back 22

- don't need to use a counter variable to control the iterations because it automatically knows the number of elements in an array

- don't need to worry about stepping outside the bounds of an array

Front 23

What is the general format of a range-based for loop?

Back 23

for (dataType rangeVariable : array)

statement;

dataType: data type of range variable must be the same as data type of array elements, or a type that they can be automatically converted to

rangeVariable: name of the variable that receives the value of the array elements during each iteration

array: name of the array for which you wish the loop to operate.

statement: statement that executes during a loop iteration

Front 24

What does auto mean when it is used in a range-based for loop?

Back 24

key word that automatically specifies the range variable's data type

int numbers[] = {1, 2, 3}
for (auto val : numbers)
cout << val;

Front 25

How can you make a range-based for loop to modify the contents of an array?

Back 25

declare the range variable as a reference variable by including & in front of its name in the loop header

for (int &val : numbers){

cout << "Enter an integer value: ";

cin >> val;}

Front 26

When can you use a range-based for loop and when do you need to use a regular for loop?

Back 26

range-based: use in any situation where you need to step through the elements of an array and you do not need to use the element subscripts

regular for: use if you need the element subscript for some reason

Front 27

How are individual array elements processed?

Back 27

processed like any other type of variable

e.g., pay = hours[3]*rate;

++hours[2];

hours[2]++;

Front 28

What do you need to be careful of when using increment/decrement operators with arrays?

Back 28

don't confuse the subscript with the array element

amount[count--]; vs. amount[count]--;

Front 29

How do you assign one array to another?

Back 29

assign the individual elements in the arrays, usually best done with a loop

for (int count=0; count

newValues[count]=oldValues[count];

Front 30

You have an array named numbers. Why is this wrong?

cout << numbers;

What do you do instead?

Back 30

it interprets the name of the array as its address in memory, not its contents

Instead, use a loop to display the contents of the array's elements
for (int count=0; count < SIZE; count++)
cout << numbers[count];
or range-based for loop
for (int val : numbers)
cout << val;

Front 31

How do you sum the values in an array?

Back 31

Use a loop with an accumulator variable

for (int val : units)

total +=val;

for (int count=0; count

total +=units[counts]

Front 32

How do you find the average of the values in an array?

Back 32

const int NUM_SCORES=10;

double scores[NUM_SCORES];

double total=0, average;

for (int val : scores)

total += val;

average = total/NUM_SCORES;

Front 33

How do you find the highest and lowest values in a numeric array?

Back 33

copy the first element to a very

use a loop to go through all elements

if the new element is > or < that one, assign it to be the new highest or lowest

Front 34

When you process a partially filled array, you must only process the elements that contain _____ ______ _______

Back 34

valid data items

Front 35

A partially filled array is normally used with an accompanying _________ variable that holds the number of items to be stored in the arrray

Back 35

integer

Front 36

How do you determine whether two arrays are equal?

Back 36

Compare the individual elements. If you do array1[]==array2[], it will test whether their memory locations are the same

e.g., use a while loop to compare the element. use a bool variable to flag whether they are still equal. use a counter to step through each element

Front 37

What does it mean to use parallel arrays?

Back 37

using the same subscripts to build relationships between data stored in two or more arrays

Front 38

When is an example of a time that it's useful to store data in two or more arrays?

Back 38

different types of data

Front 39

How do you pass a single element of an array to a function? The full array?

Back 39

Single element: handled like any other variable

function (array[0]); // don't need to do anything special w/ function parameters

Full array: pass the name of the array

function(array);

Front 40

When an entire array is passed to a function, it is passed by _______, not by _________

Back 40

reference, not value

(copying arrays would be very resource intensive)

Front 41

How do you set up a function to expect an array as a parameter?

Back 41

set up the function parameters to expect an arrayint function (int []); <-- function prototype that expects an array

Front 42

How do you prevent a function from making changes to an array argument?

Back 42

use const in the parameter declaration

void showValues (const int[]);

Front 43

As a precaution, you should always use _______ array parameters in any function that is not intended to modify its array argument

Back 43

const

That way, the code will fail to compile if you inadvertently write code that modifies the array

Front 44

When are two-dimensional arrays useful?

Back 44

storing multiple sets of data (think rows and columns)

Front 45

How do you define a two dimensional array?

Back 45

use two size declarators

double scores [3][4];

first one: rows

second one: columns

Front 46

How do you refer to a single element in a two-dimensional array?

Back 46

use both subscripts

scores [0][1]

row 0, column 1

Front 47

How do programs typically cycle through all elements of two-dimensional arrays?

Back 47

Nested loops (go through all iterations of columns for every row)

Front 48

How do you initialize a two-dimensional array?

Back 48

Enclose each row's initialization list in a set of braces

int hours [3][2] = {{8,5}, {7,9}, {6,3}}

//hours [0][0] = 8

// hours [0][1] = 5

// hours [1][0] = 7

// hours [1][1]=9

Front 49

Are the extra set of braces in the initializations of two-dimensional arrays mandatory?

Back 49

No, but they help visually separate it

Front 50

How do you set up a function to accept a two-dimensional array?

Back 50

Must specify the number of columns in the function prototype and header

void showArray (int [][4], int);

Front 51

How do you sum all elements of a two-dimensional array?

Back 51

use nested loops to add the contents of each element to an accumulator

Front 52

How do you sum the rows of a two-dimensional array?

Back 52

use a single loop to add all elements in one row

Front 53

Does C++ limit the number of dimensions an array may have?

Back 53

No. It is possible to create array with multiple dimensions to model data that occur in multiple sets

Front 54

It is helpful to think of three-dimensional arrays as _______ of two-dimensional arrays

Back 54

pages

Front 55

When writing functions that accept multi-dimensional arrays as arguments, ___ ___ ___ ___ ___ must be explicitly stated in the parameter list

Back 55

all but the first dimension

must be explicitly stated in the parameter list

Front 56

What is the STL?

Back 56

Standard Template Library

collection of programmer-defined data types and algorithms

Front 57

The data types in STL are called ______ because ________

Back 57

containers: store and organize data

Front 58

What are the two types of containers in STL?

Back 58

sequence container: organizes data sequentially, like an array

associative container: organizes data with keys, allowing for rapid, random access

Front 59

Describe the vector data type in STL. What kind of container is it? How is it similar to an array? What are the advantages over an array?

Back 59

sequence container

Similarities: stores a sequence of values in contiguous memory; can use array subscript [ ] to read individual elements

Advantages: don't have to declare the number of elements, automatically increases size to accommodate new values, can report the number of elements they contain

Front 60

What header file do you include in order to use vectors? What namespace?

Back 60

vector

using namespace std;

Front 61

How do you define a vector?

Back 61

vector < int >numbers;

//vector < data type > variableName;

Don't have to define starting size because it increases automatically, but you can if you feel like it

vector numbers (10); //size is in (), not []

Front 62

How do you copy an initialization value to all elements of a vector?

Back 62

vector numbers (10, 2);

// vector with 10 elements. Each element is assigned to 2

Front 63

How do you initialize a new vector with values from a vector that is already defined?

Back 63

vector set2 (set1);

// set2 will be a copy of set1

Front 64

How do you initialize a vector with a list of values?

Back 64

vector numbers {3, 5, 9, 10};

// do not use = to assign values

// automatically creates a vector with 4 elements

Front 65

How do you store and retrieve a value in an element that already exists in a vector?

Back 65

Use subscript operator [ ]

Front 66

Can you use a range-based for loop with vectors?

Back 66

Yes

vector numbers { 10, 20 , 30};

for (int val : numbers)

cout << val << endl;

Front 67

Can you use reference variables with vectors?

Back 67

Yes

vector numbers(5); // vector w/ 5 elements

for (int &val : numbers){

Front 68

How do you store a value in a vector that does not have a starting size or that is already full?

Back 68

use the push_back member function

(pushes the value onto the back of the vector)

e.g.,

numbers.push_back(25);

Front 69

How do you determine the size of a vector?

Back 69

size member function

numValues = vectorName.size();

useful when writing functions that accept vectors as arguments; continue while count

Front 70

How do you remove the last element from a vector?

Back 70

pop_back

vectorName.pop_back();

// removes last element from vectorName

Front 71

How do you clear a vector?

Back 71

vectorName.clear();

Front 72

How do you detect an empty function?

Back 72

vectorName.empty();

Front 73

How can you break out of a loop when a user enters a sentinel value?

Back 73

break

for loop{

// stuff

if (value == sentinel #) break; // will break out of loop

Front 74

How do you return the value located at a specific element in the vector?

Back 74

at(element)

x = vectorName.at(5); // returns value stored in 5th element

Front 75

How do you return the maximum number of elements that can be stored in a vector without additional memory being allocated?

Back 75

capacity()

x = vectorName.capacity();

Front 76

How do you reverse the order of elements in a vector?

Back 76

reverse()

vectorName.reverse();

Front 77

How do you resize a vector by a certain number of elements?

Back 77

resize (elements, value)

vectorName.resize (5,1);

//increase the size of the vector by 5 and initializes all 5 new elements to 1

Front 78

How do you swap the contents of two vectors?

Back 78

swap

vector1.swap(vector2);