Understanding Arrays in C Programming

What is Array

An array is a collection of the same type of data items, which are stored in consecutive memory locations under a common name.

Features of Array

• An array is a linear data structure.
• An array can store many values using a single variable name.
• Arrays store elements of the same data type.
• Every element has an index number. Array elements can be accessed quickly using index numbers.
• Array elements are stored in continuous memory locations.

Types of Array

There are two types of Arrays :

1. One-Dimensional Array

A One-dimensional array is an array in which only one index is used to access or specify an element of the array.

Declaration of One-Dimensional Array

In C, One-dimensional array can be declared as follows:

Here, array_name is the name of the array, and array_size represents how many elements the array can store. The data_type specifies the type of data stored in the array, such as int, float, or char. The size of the array must be a whole number.

For example int array[5];

Initialization of One-Dimensional Array

In C, One-dimensional array can be initialized in two ways.

• Initialization with Declaration

In this method, values are assigned to the array at the time of declaration as follows:

For example: int array[] = {1, 2, 3, 4, 5};. Here, it is not necessary to define size of array.

• Initialization After Declaration

In this method, the array is declared first, and values are assigned later using indexes as follows:

For example: if int array[5]; then array[0] = 1;. Now, first element of array is 1.

#include <stdio.h>

int main() {

    int arr[] = {2, 4, 8, 12, 16, 18};

    int n = sizeof(arr)/sizeof(arr[0]);

    // Printing array elements

    for (int i = 0; i < n; i++) {

        printf("%d ", arr[i]);

    }

    return 0;

}

Operations Perform on Arrays

1. Traversing

Traversing means accessing and displaying each element of an array one by one.

C Program for Traversing Array:

#include <stdio.h>

int main() {

    int arr[5] = {10, 20, 30, 40, 50};

    for(int i = 0; i < 5; i++) {

        printf("%d ", arr[i]);

    }

    return 0;

}

2. Insertion

Insertion means adding a new element into an array at a specific position.

C Program for Insertion

#include <stdio.h>

int main() {

    int arr[6] = {10, 20, 30, 40, 50};

    int pos = 2;

    int value = 25;

    int n = 5;

    for(int i = n; i > pos; i--) {

        arr[i] = arr[i - 1];

    }

    arr[pos] = value;

    n++;

    for(int i = 0; i < n; i++) {

        printf("%d ", arr[i]);

    }

    return 0;

}

3. Deletion

Deletion means removing an element from an array. After deletion, remaining elements are shifted left.

C Program for Deletion

#include <stdio.h>

int main() {

    int arr[5] = {10, 20, 30, 40, 50};

    int pos = 2;

    int n = 5;

    for(int i = pos; i < n - 1; i++) {

        arr[i] = arr[i + 1];

    }

    n--;

    for(int i = 0; i < n; i++) {

        printf("%d ", arr[i]);

    }

    return 0;

}

4. Merging

Merging means combining two arrays into a single array.

C Program for Merging Arrays

#include <stdio.h>

int main() {

    int arr1[3] = {1, 2, 3};

    int arr2[3] = {4, 5, 6};

    int arr3[6];

    for(int i = 0; i < 3; i++) {

        arr3[i] = arr1[i];

    }

    for(int i = 0; i < 3; i++) {

        arr3[i + 3] = arr2[i];

    }

    for(int i = 0; i < 6; i++) {

        printf("%d ", arr3[i]);

    }

    return 0;

}

5. Searching

Searching means finding whether an element exists in an array or not.

C Program for Searching

#include <stdio.h>

int main() {

    int arr[5] = {10, 20, 30, 40, 50};

    int item = 30;

    int found = 0;

    for(int i = 0; i < 5; i++) {

        if(arr[i] == item) {

            found = 1;

            printf("Element found at index %d", i);

            break;

        }

    }

    if(found == 0) {

        printf("Element not found");

    }

    return 0;

}

6. Sorting

Sorting means arranging array elements in a particular order such as ascending or descending order.

C Program for Sorting Array

#include <stdio.h>

int main() {

    int arr[5] = {50, 20, 40, 10, 30};

    int temp;

    for(int i = 0; i < 5; i++) {

        for(int j = i + 1; j < 5; j++) {

            if(arr[i] > arr[j]) {

                temp = arr[i];

                arr[i] = arr[j];

                arr[j] = temp;

            }

        }

    }

    for(int i = 0; i < 5; i++) {

        printf("%d ", arr[i]);

    }

    return 0;

}