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Arrays in C

Arrays in C are used to store multiple values of the same type in a single variable. They are fixed in size and can be accessed using indices. Arrays are one of the most fundamental data structures in C.

Declaring Arrays

Arrays are declared using the syntax: type array_name[size];. Here, type is the data type of the elements, array_name is the name of the array, and size is the number of elements the array can hold. 


#include <stdio.h>

int main() {
    // Declare an array of 5 integers
    int numbers[5] = {1, 2, 3, 4, 5};

    // Access and print array elements
    for (int i = 0; i < 5; i++) {
        printf("%d\n", numbers[i]);
    }
    return 0;
}

Initializing Arrays

Arrays can be initialized at the time of declaration. If the size is omitted, the compiler determines the size based on the number of elements provided. 


#include <stdio.h>

int main() {
    // Initialize array without specifying size
    int numbers[] = {10, 20, 30, 40, 50};

    // Calculate size of the array
    int size = sizeof(numbers) / sizeof(numbers[0]);

    // Print array elements
    for (int i = 0; i < size; i++) {
        printf("%d\n", numbers[i]);
    }
    return 0;
}

Multidimensional Arrays

C supports multidimensional arrays, such as 2D arrays, which are often used to represent matrices or tables. 


#include <stdio.h>

int main() {
    // Declare and initialize a 2D array
    int matrix[2][3] = {
        {1, 2, 3},
        {4, 5, 6}
    };

    // Access and print 2D array elements
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            printf("%d ", matrix[i][j]);
        }
        printf("\n");
    }
    return 0;
}

Dynamic Arrays

In C, dynamic arrays can be created using pointers and memory allocation functions like malloc and free. 


#include <stdio.h>
#include <stdlib.h>

int main() {
    int size;

    // Get array size from user
    printf("Enter the size of the array: ");
    scanf("%d", &size);

    // Allocate memory dynamically
    int *numbers = (int *)malloc(size * sizeof(int));

    // Check if memory allocation was successful
    if (numbers == NULL) {
        printf("Memory allocation failed!\n");
        return 1;
    }

    // Input array elements
    printf("Enter %d elements:\n", size);
    for (int i = 0; i < size; i++) {
        scanf("%d", &numbers[i]);
    }

    // Print array elements
    printf("Array elements: ");
    for (int i = 0; i < size; i++) {
        printf("%d ", numbers[i]);
    }
    printf("\n");

    // Free allocated memory
    free(numbers);
    return 0;
}

Common Array Operations

Arrays are often used for operations like searching, sorting, and traversing. Below are some examples:

Searching in an Array


#include <stdio.h>

int main() {
    int numbers[] = {10, 20, 30, 40, 50};
    int size = sizeof(numbers) / sizeof(numbers[0]);
    int target = 30;
    int found = 0;

    // Linear search
    for (int i = 0; i < size; i++) {
        if (numbers[i] == target) {
            printf("Element found at index %d\n", i);
            found = 1;
            break;
        }
    }

    if (!found) {
        printf("Element not found\n");
    }
    return 0;
}

Sorting an Array


#include <stdio.h>

void bubbleSort(int arr[], int size) {
    for (int i = 0; i < size - 1; i++) {
        for (int j = 0; j < size - i - 1; j++) {
            if (arr[j] > arr[j + 1]) {
                // Swap elements
                int temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
            }
        }
    }
}

int main() {
    int numbers[] = {50, 20, 40, 10, 30};
    int size = sizeof(numbers) / sizeof(numbers[0]);

    // Sort the array
    bubbleSort(numbers, size);

    // Print sorted array
    printf("Sorted array: ");
    for (int i = 0; i < size; i++) {
        printf("%d ", numbers[i]);
    }
    printf("\n");
    return 0;
}

Advantages of Arrays

Limitations of Arrays

Pointers