[#7] – Arrays and Strings – Questions

C-plus-plus-programming-questions-techhyme

An array is a collection of logically related variables of identical data type that share a common name. It is used to handle large amount of data, without the need to declare many individual variables separately. The array elements are stored in a contiguous memory locations. All the array elements must be either of any primitive data types like int, float, char, double etc. or they can be of any user-defined data types like structure and objects.

Index:

Each array element is accessed and manipulated using an array name followed by a unique index or subscript that specify the position within the array. A single subscript is required to access an element of one-dimensional array and two subscripts are required to access an element of two dimensional array. All the arrays whose elements are accessed using two or more subscripts are called multidimensional arrays. It should be kept in mind that each subscript is enclosed in square brackets and it should be expressed as a non-negative integer constant or expression.

Key Points To Remember –

An array is a collection of logically related variables of identical data type that share a common name. The array elements are stored in a contiguous memory locations. Each array element is accessed and manipulated using an array name followed by a unique index that specifies the position within the array.
The storage space allocated to an array is equal to the maximum number of elements multiplied by the size of datatype used.
Arrays are of two types- one dimensional array and multi-dimensional array.
When an array is passed to a function, it is passed by reference and not by value which means that elements of an array are not copied to the function but the array name is interpreted as the address of its first element. Any changes made are reflected back to original array.
A two-dimensional array are generally used to store table of values in such a way that information is arranged in ‘rows’ and ‘columns’.
Two dimensional array can also be initialized with list of values in such a way that elements of first row are initialized first followed by elements of second row and so on.
A string is a collection of characters terminated by a null character ( ‘\0’) which specifies where the string terminates in memory. A string can be represented as a one-dimensional char type array where each character of the string is stored as an element of an array.
strlen(), strrev(), strcpy(), strcmp() are some of the commonly used string handling functions. The prototypes of these functions are specified in the header file string.h.
An array of strings can be represented by a two-dimensional array where the first size specification tells the number of strings and the second size specification tells the number of characters in each string.

Viva Voce Questions –

Here are commonly asked questions with answers:

Why is it better to use symbolic names for size specification in arrays ?
- It becomes easier to modify a program by simply making changes in the value of symbolic constant.
What is the benefit of contiguous memory allocation in arrays ?
- By knowing the address of the first elements Of the array.
Why do array subscripts start from 0 instead of 1 ?
- Starting the subscript from 0 simplifies the job of the compiler for handling arrays. Also, it makes the array subscripting marginally faster.
Is it possible to specify a character as an array subscript ?
- Yes, because every character has an ASCII value associated with it which is an integer.
If a and b are two arrays of same type, can the statement a=b, work ?
- No, two arrays can be copied using the statement a=b; It can be done as for (int i=0;i<n;i++)
  a[i]=b[i];
What will be the output of following program segment.
main()
{
…………………………..
int i=1;
int a[4]={1,2,3,4};
f1(a[i], i++);
…………………………..
}
void f1 (int a, int b)
{
cout<<a<<‘\t'<<b;
}
- 3 2
  This is because during function call, a stack is maintained in which actual arguments are pushed from right to
  left f(a[i],i++) ;
  First, i++=2 Then a[i=a[2]=3
Is it essential for strings to end with ‘\0’ ?
- Yes, because this is the only way the compiler comes to know that end of string is encountered.
What are different ways by which strings can be assigned values ?
- Through initialization. E.g. char sl[]=” Ankur”;
- Using strcpy() function. E.g. strcpy (sl,”Helo”),
- Using input functions. E.g. get() or extraction operator functions
What is the difference between inputting a string using get() function and extraction operator (>>) function ?
- get() can input multi line string whereas extraction operator cannot input multi word, multi line string.