11.5 SORTING ARRAY Sorting is the process of transforming a list into an equivalent list, in which the elements are arranged in ascending or descending.

11.5 SORTING ARRAY

• Sorting is the process of transforming a list

• into an equivalent list, in which the elements are arranged in ascending or descending order.

•A sorting list is called an ordered list.

•arr[0]<= arr[1] <= ….,<= arr[n-2]<=arr[n-1]

Bubble Sort

• Comparing two consecutive array elements and swapping them if the first is greater than the second.

• At the end of the first pass,we have succeeded in pushing the largest value in the array to its end .

• Fig 11.9 A C function that sorts an array using bubble sort .

• typedef int list_item_type;

Selecting Sort

• Of selecting the largest array element and swapping it with the last array element .

• Figure 11.11 A C function that sorts an array using selection sort

Insertion Sort

• Of inserting a new item into a list of ordered items.

• Figure 11.13 A C function that sorts an array using insertion sort .

Constructing a Sort Library

• Figure 11.14 the header file sort.h for the

• programmer-defined sort library.

• #include “sort.h”.

11.6 SEARCHING ARRAYS

• We search a list stored in an array to determine whether it contains an element that matching a given

Sequential Search

• We access list elements , starting with the first ,and compare each element with the search key.

• If we find a match , the search is successful.

• If we access and compare the last list element and still have no match , then the search is unsuccessful.

• Improve the efficiency of this algorithm by running it on ordered list .

• Algorithm terminates if the search key value turns out to be less than an array element.

Binary Search

• Compares the search key value with the value of the list element that is midway in the list .

• Figure 11.20 A C function that searches an array using binary search

• Figure 11.21 Comparing efficiencies of sequential and binary search

• List_size sequential search binary search

• 100 100 7

• 1,000,000 1,000,000 20

• 1,000,000,000 1,000,000,000 30

Constructing Search Library

• #include “search.h”

• #include <string.h>

11.7 EXAMPLE PROGRAM 2:

A C Program that Creates, Sort, and Searches a One-Dimensional

Array of Integers

11.8 HIGHT –DIMENSIONAL ARRAYS

• An array of one-dimensional arrays is called • a two-dimensional arrays;• An array of two-dimensional arrays is called a

three-dimensional array,and so on.

A two-dimensional arrays is equivalent to a table of a fixed number of rows and a fixed number of columns .

Declaring Two-Dimensional Arrays

• int test_scores[4][3]; • The first subscript is the number of rows, and the second is t

he number of columns.• When the complier encounters the declaration for a two-dim

ensional array,it allocates memory locations for its elements in a linear fashion.

• The memory locations for the elements on row 0 are followed by the memory locations for the elements on row 1;

Initialization of Two-Dimensional arrays

• int test_scores[4][3]=

• {95,80,78,69,75,81,100,98,100,98,85,87};

• int test_scores[][3]=

• {{95,80,78},{69,75,81},{100,98,100},{98,85,87}};

Operations on Two–Dimensional Arrays

• If we declare a two-dimensional array in the formal parameter list as int b [][],

• Each element of the one-dimensional array is a one-dimensional array.

• We must also tell the complier about the number of elements in each row of the two-dimensional array.

• Therefore in the formal parameter list the proper declaration must be as int b[][20],thus enabling the complier to compute the offset for the second row as 2*20=40.

The rules for passing two-dimensional arrays to functions

• 1. Be declared

• void input_tale(int *no_of _rows ,

• int *no_of_columns,

• int arr[][COLUMNS_SIZE]);

• 2.in its prototype.

• void input_tale(int *no_of _rows ,

• int *no_of_columns,

• int arr[][COLUMNS_SIZE]);

• 3. In a call

• input_table(&rows, &columns , test_scores );

Two-Dimensional Arrays and Pointers

• int t[4][3]

• t as a pointer to row 0.

• *t a pointer to t[0][0].

• We can access its content by again applying the indirection operator as *(*t).

• it is *t+1 ,and the reference to t[0][1] in pointer/offset notion is *(*t+1).

• The pointer to row 1 is t+1 .

• For example , the pointer to the third element in row 1 is *(t + 1 ) +2 ,and the name of that element is *(*(t + 1) +2).

• *(*( t + i ) + j) is the name of the array element t[i][j] in pointer/offset notation

• for (i=0; i<4; i++)

• { printf (“\nROW %d OF array t: “, i);

• for (j=0 ; j<3 ; j++)

• printf (“%d” , t[i][j]);

• /*end for */

• } /* end for */

• for (i=0 ; i < 4 ; i++ )

• { printf (“\nROW %d OF array t: “, i);

• for (j=0 ; j<3 ; j++)

• printf (“%d” , *(* t + i ) + j );

• /*end for */

• } /* end for */

• Suggest that you avoid using pointer/offset notation unless program efficiency for compilation turns out to be very important in you application.

11.9 EXAMPLE PROGRAM 3:A C Function that Generates a Ba

r Chart