## Arrays

[ICSE Syllabus on this Topic]

Array and their usage, sorting algorithm – selection sort and bubble sort, search in sorted array. The class objects compatible with all the class.

Q. What do you understand by Arrays? How you declare an Array?

Ans: An Array is a collection of variables of the same data type that are referenced by a common name. Array can be declared by the following statements: int n[]=new int[10];

Q. What are the different types of arrays?

(i) Single Dimensional Arrays: A list of items can be given one variable name using only one subscript and such a variable is called a single subscripted variable or a one or single dimensional array.

(ii) Multi Dimensional Arrays: This type of arrays are actually arrays of arrays.

Q. Why we use Arrays? or What are the Advantages of using Arrays.

Ans: The Advantages or Arrays are: (i) Easy to Specify. (ii) Free from run-time overload. (iii) Random access of elements. (iv) Fast Sequential Access.

Q. How can arrays be initialized?

Ans: Array can be initialized at the time of declaration by providing the value list at the same time.

Q. What do you understand by out-of-bound subscripts?

Ans: The subscripts other than 0 to n-1 for an array having n elements are called out-of-bounds subscripts.

Q. What do you mean by Binary Search?

Ans: This search technique searches the given ITEM in minimum possible compression. The Binary search requires the array must be sorted in any order. The search ITEM is compared with middle element of the array. If the ITEM is more then the middle element later part of the arrays becomes the new array segment. The same process is repeated until either the ITEM is found or the array segment is reduce to single element.

Q. Differentiate between linear search and binary search techniques?

Ans: In linear search each elements of the array is compared with the given item to be searched for one by one while binary search searches for the given item in a sorted array. The search segment reduces to half at every successive stage.

Q. State the conditions under which Binary Search is applicable?

Ans: For Binary Search The List must be sorted, lower bound upper bound and the sort order of the list must be known.

Q. Comment on the efficiency of linear search and Binary Search in relation to the number of element in the list being searched?

Ans: The Linear search compares the search item with each element of the array, one by one. If the search item happens to be in the beginning of the array, the compressions are low, however if the element to be searched for is one of the last elements of the array, this search technique proves the worst as so many comparisons take place. The Binary search on the other hand, tries to locate the search item in minimum possible comparisons, provided the array is sorted. This technique proves efficient in nearly all the cases.

Q. What do you mean by sorting?

Ans: Sorting of an array means arranging the array elements in a specified order.

Q. What is Selection sort?

Ans: In selection sort the smallest ( or largest depending upon the desired order) key from the remaining unsorted array is searched for and put in the sorted array. The process repeats until the entire array is sorted.

Q. What is Bubble sort?

Ans: In bubble sort the adjoining values are compared and exchanged if they are not in proper order. This process is repeated until the entire array is sorted.

Q. Which element is num[9] of the array num?

Ans: 10th element. Because the first index number/subscript value of an array is 0. So 9th element is treated as the 10th element in an array.