The array is a container for a certain number of elements, all of which must be of the same type. Arrays are used by the majority of data structures to implement their algorithms. The following are some key terms to know in order to grasp the notion of Array.
Element − Each item stored in an array is called an element.
Index − Each location of an element in an array has a numerical index, which is used to identify the element.
Array Representation
Arrays can be declared in various ways in different languages. For illustration, let's take C array declaration.
As per the above illustration, the following are the important points to be considered.
- Index starts with 0.
- Array length is 8 which means it can store 8 elements.
- Each element can be accessed via its index. For example, we can fetch an element at index 6 as 9.
Basic Operations
Following are the basic operations supported by an array.
Traverse − print all the array elements one by one.Insertion − Adds an element at the given index.Deletion − Deletes an element at the given index.Search − Searches an element using the given index or by the value.Update − Updates an element at the given index.
In C, when an array is initialized with size, then it assigns defaults values to its elements in the following order.
| Data Type | Default Value |
|---|
| bool | false |
| char | 0 |
| int | 0 |
| float | 0.0 |
| double | 0.0f |
| void | |
| wchar_t | 0 |
Insertion Operation
- One or more data elements are inserted into an array using the insert operation. A new element can be added to the beginning, end, or any provided index of the array, depending on the necessity.
- We can see an actual implementation of the insertion action here, where we add data to the array's end.
Algorithm
Let Array be a linear unordered array of MAX elements.
Example
Result
Let LA be a Linear Array (unordered) with N elements and K is a positive integer such that K<=N. Following is the algorithm where ITEM is inserted into the Kth position of LA −
1. Start
2. Set J = N
3. Set N = N+1
4. Repeat steps 5 and 6 while J >= K
5. Set LA[J+1] = LA[J]
6. Set J = J-1
7. Set LA[K] = ITEM
8. Stop
Example
Following is the implementation of the above algorithm −
#include <stdio.h>
main() {
int
LA[] = {1,3,5,7,8};
int
item = 10, k = 3,
n = 5;
int
i = 0, j =
n;
printf("The
original array elements are :\n");
for(i = 0;
i<n;
i++) {
printf("LA[%d]
= %d \n", i,
LA[i]);
}
n =
n + 1;
while( j >= k) {
LA[j+1] =
LA[j];
j =
j - 1;
}
LA[k] = item;
printf("The array elements after insertion :\n");
for(i = 0;
i<n;
i++) {
printf("LA[%d]
= %d \n", i,
LA[i]);
}
}
When we compile and execute the above program, it
produces the following result −
Output
The original array elements are :
LA[0] = 1
LA[1] = 3
LA[2] = 5
LA[3] = 7
LA[4] = 8
The array elements after insertion :
LA[0] = 1
LA[1] = 3
LA[2] = 5
LA[3] = 10
LA[4] = 7
LA[5] = 8
Deletion Operation
- Deletion refers to removing an existing element from the
array and re-organizing all elements of an array.
Algorithm
- Consider LA is a linear array with N elements
and K is a positive integer such that K<=N.
Following is the algorithm to delete an element available at the Kth position
of LA.
1. Start
2. Set J = K
3. Repeat steps 4 and 5 while J < N
4. Set LA[J-1] = LA[J]
5. Set J = J+1
6. Set N = N-1
7. Stop
Example
Following is the implementation of the above algorithm −
#include <stdio.h>
main() {
int
LA[] = {1,3,5,7,8};
int
k = 3, n = 5;
int
i, j;
printf("The
original array elements are :\n");
for(i = 0;
i<n;
i++) {
printf("LA[%d]
= %d \n", i,
LA[i]);
}
j =
k;
while( j < n) {
LA[j-1] =
LA[j];
j =
j + 1;
}
n =
n -1;
printf("The
array elements after deletion :\n");
for(i = 0;
i<n;
i++) {
printf("LA[%d]
= %d \n", i,
LA[i]);
}
}
When we compile and execute the above program, it
produces the following result −
Output
The original array elements are :
LA[0] = 1
LA[1] = 3
LA[2] = 5
LA[3] = 7
LA[4] = 8
The array elements after deletion :
LA[0] = 1
LA[1] = 3
LA[2] = 7
LA[3] = 8
Search Operation
You can perform a search for an array element based on
its value or its index.
Algorithm
Consider LA is a linear array with N elements
and K is a positive integer such that K<=N.
Following is the algorithm to find an element with a value of ITEM using
sequential search.
1. Start
2. Set J = 0
3. Repeat steps 4 and 5 while J < N
4. IF LA[J] is equal ITEM THEN GOTO STEP 6
5. Set J = J +1
6. PRINT J, ITEM
7. Stop
Example
Following is the implementation of the above algorithm −
#include <stdio.h>
main() {
int
LA[] = {1,3,5,7,8};
int
item = 5, n = 5;
int
i = 0, j = 0;
printf("The
original array elements are :\n");
for(i = 0;
i<n;
i++) {
printf("LA[%d]
= %d \n", i,
LA[i]);
}
while( j < n){
if( LA[j] == item ) {
break;
}
j =
j + 1;
}
printf("Found
element %d at position %d\n",
item, j+1);
}
When we compile and execute the above program, it
produces the following result −
Output
The original array elements are :
LA[0] = 1
LA[1] = 3
LA[2] = 5
LA[3] = 7
LA[4] = 8
Found element 5 at position 3
Update Operation
- Update operation refers to updating an existing element
from the array at a given index.
Algorithm
- Consider LA is a linear array with N elements
and K is a positive integer such that K<=N.
Following is the algorithm to update an element available at the Kth position
of LA.
1. Start
2. Set LA[K-1] = ITEM
3. Stop
Example
Following is the implementation of the above algorithm −
#include <stdio.h>
main() {
int
LA[] = {1,3,5,7,8};
int
k = 3, n = 5,
item = 10;
int
i, j;
printf("The
original array elements are :\n");
for(i = 0;
i<n;
i++) {
printf("LA[%d]
= %d \n", i,
LA[i]);
}
LA[k-1] =
item;
printf("The
array elements after updation :\n");
for(i = 0;
i<n;
i++) {
printf("LA[%d]
= %d \n", i,
LA[i]);
}
}
When we compile and execute the above program, it
produces the following result −
Output
The original array elements are :
LA[0] = 1
LA[1] = 3
LA[2] = 5
LA[3] = 7
LA[4] = 8
The array elements after updation :
LA[0] = 1
LA[1] = 3
LA[2] = 10
LA[3] = 7
LA[4] = 8
We choose B, mark it as visited and put onto the stack. Here B does not have any unvisited adjacent node. So, we pop B from the stack.
