lecture 9&10

Question 1

what’s an array ?

Answer 1

Array is a variable that can store multiple values of the same type

Question 2

how are the values in the array stored in the memory ?

Answer 2

they are stored in adjacent memory locations

Question 3

label the following array definition :

int tests[5];

Answer 3

• int is the data type of the array elements
• tests is the name of the array
• 5, in [5], is the size declarator. It shows the NUMBER of elements in the array.

Question 4

what is the difference between the size of an array and the size declarator of an array ?

Answer 4

• the size declarator shows the NUMBER of elements in the array. ex:- int array [ 6 ] ; is an array with size declaraor of , meaning the array has 6 elements.
• the size of an array is the total number of bytes
  = (number of elements) * (size of each element)
  ex:- int array [ 6 ] ; is an array of size (6 * 4 bytes ) = 24 bytes

Question 5

cout &laquo_space;tests ; // why would this give an error ?

what is the only case in which this cout - statement wont give an error ?

Answer 5

Arrays must be accessed via individual elements ex:-
cout &laquo_space;tests[0];
cin&raquo_space; tests[1];

the ONLY case in which we can display the contents of the whole array by sending only its name to cout is if the tests [ ] array is a character array

ex:-

char tests [ ] = “henry”;
cout &laquo_space;tests ;

Question 6

Default Initialization for arrays :

• Global array → all elements ………. by default
• Local array → all elements ………….by default

Answer 6

• initialized to 0
• uninitialized

Question 7

Arrays can be initialized with an…………… that cannot exceed the array size.
If array is initialized with fewer initial values than the size declarator, the remaining elements…………..

Answer 7

• initialization list
• will be set to 0

Question 8

we Can determine array size by the size of the initialization list. ex:-
int quizzes [ ] ={12,17,15,11};

we Must use either ……………… or………. at array definition

Answer 8

array size declarator or initialization list

Question 9

what is the difference between
tests[ i ] ++ ; and tests [ i ++] ; ??

Answer 9

tests[i]++; // add 1 to tests[i]
tests[i++]; // increment i, no effect on tests[ i ]

Question 10

to copy an array , assign each element of array 1 to the corrosponding element in array 2 by using loop
ex:-
newTests = tests ; // Won’t work ERROR

Answer 10

for (i = 0 ; i < ARRAY_SIZE ; i++)
newTests [ i ] = tests[ i ];

Question 11

Most compilers do not allow the use of a variable to declare the size of an array
ex:-
cout &laquo_space;“Enter number of students: “;
cin&raquo_space; number;
int score[number]; // IS ILLELGAL

Answer 11

solution :
Make the array large enough to hold the
largest expected number of elements.
*Use a counter variable to keep track of the
number of items stored in the array

Question 12

what are parallel arrays ?

Answer 12

• Parallel arrays are two or more arrays that contain related data
• elements at same subscript are related
• Arrays may be of different types

Question 13

changes made to array in a function are reflected in actual array in calling function like reference variables

Functions can NOT return array type . instead we return a ………..

Answer 13

pointer to an array

Question 14

array can store objects as its elements
and the ……………… for the object is used when array is defined .
or use ………. to invoke constructor that takes arguments

Answer 14

Default constructor
the initializer list

Question 15

Objects in an array are referenced using ………….
Member functions are referenced using ……….

Answer 15

• subscripts
• dot notation

Question 16

*Declare a vector to hold int element:
……………………………….
*Declare a vector with initial size 30:
………………………………..
*Declare a vector and initialize all elements to 0:
……………………………….
*Declare a vector initialized to size and contents of
another vector:
…………………………….

Answer 16

• vector<int> scores ;</int>
• vector<int> scores(30) ;</int>
• vector<int> scores(30, 0) ;</int>
• vector<int> finals(scores) ;</int>

Question 17

• Use …………. member function to add element to a full array or to an array that had no defined size
• Use …………. member function to determine size of a vector:

Answer 17

• push_back
  ex:-
  scores.push_back(75) ;
• size
  ex:-
  howbig = scores . size() ;

Question 18

*Use …………. member function to remove last
element from vector

• To remove all contents of vector, use ……..member function
• To determine if vector is empty, use ………member function

Answer 18

• pop_back ex:- scores . pop_back() ;
• clear ex:- scores . clear() ;
• empty ex:- while ( ! scores . empty () )

Question 19

…………..Returns the value of the element at
position elt in the vector
…………….Returns the maximum number ofelements a vector can store without allocating more memory
…………..Reverse the order of the elements in a vector
………….Add elements to a vector, optionally initializes them
…………. Exchange the contents of two vectors

Answer 19

• at(elt) ex:- cout &laquo_space;vec1.at(i);
• capacity() ex:- maxelts =vec1.capacity();
• reverse() ex:- vec1.reverse();
• resize(elts,val) ex:- vec1.resize(5,0);
• swap(vec2) ex:- vec1.swap(vec2);