Programming and Data Structures

474 Programming and Data Structures

Enter eight elements: 12 34 54 76 69 78 85 97

Enter an element: 3

The element 3 is not found in list

Explanation In the above program eight elements are entered. The user has to enter an element

whose predecessor and successor are to be identified. All the elements of the array are checked with

the entered number. When the match is found, the next element of the entered number is displayed

as successor and the previous element is displayed as predecessor. If the element entered is the first

element of the list then only successor is displayed. If the entered element is the last element of the

list then only predecessor is displayed. The above conditions are checked using conditional operator

(?:).

14.7 INSERTION

When a new element is added in the list it called append. However, when an element is added in

between two elements in the list the process is called as insertion. The insertion can be done at the

beginning, inside or anywhere in the list.

For successful insertion of an element, the array implementing the list should have at least one

empty location. If the array is full, insertion cannot be possible. The target location where element is

to be inserted is made empty by shifting elements downwards by one position and the newly Inserted

element is placed at that location. Consider the Fig. 14.5.

5 7

9

10 12

0

1 2 3 4 5 6

5 7

9

10

12

0

1 2 3 4

5 6

(a) (b)

5 7

3 9 10 12

0 1

2 3 4

5 6

(c)

Fig. 14.5 Insertion

As per Fig. 14.5 (a), two empty spaces are available. Suppose we want to insert 3 in between 7 and 9.

All the elements after 7 must be shifted towards end of the array The resulting array would be as

shown in Fig. 14.5 (b). The entered number 3 can be assigned to that memory location and the array

would look like Fig. 14.5 (c). Fig. 14.5 describes the insertion of an element.

Linear Data Structure 475

The following program illustrates the insertion operation.

14.4 Write a program to create a list. Insert some element at the specified location.

# include <stdio.h>

# include <conio.h>

# include <process.h>

main ()

{

int num[8]= {0 }, j,kaO,p,n;

c lr s c r();

printf ( ”\n Enter elements ( 0 to exit ) t ■ );

for (j«0;j<8;j+ +)

{

scanf ("%d"#&num[j]);

i f ( num[j]*»0)

break;

}

i f (j<8)

{

printf ("\n Enter Position number and element : ■);

scanf ("%d %dn,&p,&n);

--p ;

}

else

while (num[k]1=0)

k++;

k-- ;

for (j =k;j > = p ;j- -)

num[j + 1]=num [j];

num [p] =n;

for (j=0 ;j <8;j+ + )

prin tf ( M %d ”, num [j]);

}

OUTPUT:

Enter elements ( 0 to exit): 1234560

Enter Position number and element: 5 10

1 2 3 4 10 5 6 0

Explanation In the above program an array num [8] is declared. The user has to enter elements

continuously. The user can enter zero to exit from the continuous input routine. If zero is entered, the

break statement takes control out of the for loop. Thus, the list contains few empty memory locations,

which are enough to carry insertion operation. When the user enters eight elements, the program