Array in c programming

• An Array is a collection of similar data items that are stored under a common name.
• An Array in C programming can be declared in the declarative part of the program.

Array Syntax in C

data type array name [size];

Ex: int a[5];

• [0]🡪subscript.
• 10, 20, 30, 40, and 50 are values of an array.
• 0, 1, 2, 3, 4, 5 🡪index number
• an🡪array name
• [0] – 10 🡪 rows in the table indicate the location of an array.
• Each location of an array indicated by a number is called an Index number.
• The index number which is enclosed within the square brackets is called subscript. 
• The subscript of an array always starts from 0.
• The subscript of an array does not contain negative values. The values in an array may be of integer data type, real data type (float), or character data type.
• The subscript of an array is always associated with its array name.

Types of Array in C programming

There are two types of arrays based on the number of dimensions it has. They are as follows

1.One Dimensional Arrays(1D Array)

2. Multidimensional Arrays

1.One Dimensional Arrays(1D Array)

• An array which has only one subscript is called a 1-D array. In a 1-D array, the values are stored in different rows but only in one column.
• The 1-D array can be declared as global or local.
• Initializing the array: Like other variables, we can also initialize a 1-D array at the time of declaration.
• Ex: int a[5] ={10,20,30,40,50};
• The elements in the array are stored sequentially in separate memory locations.

Syntax of 1D Array in C

 array_name[size];

Example of 1D Array in C

#include <stdio.h>
int main() {
    // Declare an array of integers with 5 elements
    int arr[5];
    // Initialize the elements of the array
    arr[0] = 10;
    arr[1] = 20;
    arr[2] = 30;
    arr[3] = 40;
    arr[4] = 50;
    // Access and print elements of the array
    printf("Elements of the array:\n");
    for (int i = 0; i < 5; i++) {
        printf("arr[%d] = %d\n", i, arr[i]);
    }
    return 0;
}

Output

Elements of the array:
arr[0] = 10
arr[1] = 20
arr[2] = 30
arr[3] = 40
arr[4] = 50

2. Multidimensional Arrays

• Multi-dimensional Arrays in C are those arrays that have more than one dimension.
•  Some of the popular multidimensional arrays are 2D arrays and 3D arrays. 
• We can declare arrays with more dimensions than 3d arrays but they are avoided as they get very complex and occupy a large amount of space.

Two Dimensional Array in C(2D array)

• A Two-Dimensional array or 2D array in C is an array that has exactly two dimensions. 
• They can be visualized in the form of rows and columns organized in a two-dimensional plane

Syntax of 2D Array in C

Data type array name [size1][size2];

Example of 2D Array in C

#include <stdio.h>
int main() {
    // Declare and initialize a 2D array of integers with 2 rows and 3 columns
    int arr[2][3] = {
        {1, 2, 3},   // First row
        {4, 5, 6}    // Second row
    };
    // Access and print elements of the 2D array
    printf("Elements of the 2D array:\n");
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            printf("arr[%d][%d] = %d\n", i, j, arr[i][j]);
        }
    }
    return 0;
}

Output

Elements of the 2D array:
arr[0][0] = 1
arr[0][1] = 2
arr[0][2] = 3
arr[1][0] = 4
arr[1][1] = 5
arr[1][2] = 6

Three Dimensional Array in C(3D Array)

• A 3D array has exactly three dimensions. 
• It can be visualized as a collection of 2D arrays stacked on top of each other to create the third dimension.

Syntax of 3D Array in C

Data type array name [size1][size2][size3];

Example of 3D Array in C

#include <stdio.h>
int main() {
    // Declare and initialize a 3D array
    int arr[2][3][4] = {
        {   // 1st "depth" layer
            {1, 2, 3, 4},
            {5, 6, 7, 8},
            {9, 10, 11, 12}
        },
        {   // 2nd "depth" layer
            {13, 14, 15, 16},
            {17, 18, 19, 20},
            {21, 22, 23, 24}
        }
    };
    // Access and print elements
    printf("Element at arr[0][1][2]: %d\n", arr[0][1][2]); // Output: 7
    printf("Element at arr[1][2][3]: %d\n", arr[1][2][3]); // Output: 24
    // Iterate through all elements and print
    printf("\nAll elements:\n");
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            for (int k = 0; k < 4; k++) {
                printf("%d ", arr[i][j][k]);
            }
            printf("\n");
        }
        printf("\n"); 
    }
    return 0;
}

Output

Element at arr[0][1][2]: 7
Element at arr[1][2][3]: 24
All elements:
1 2 3 4 
5 6 7 8 
9 10 11 12 
13 14 15 16 
17 18 19 20 
21 22 23 24 

Advantages of Array in C programming

Fast Access: Look up any element instantly by its index.

Easy Iteration: Loop through elements effortlessly.

Memory Efficient: Stores elements compactly.

Versatility: A building block for many other data structures.

Performance: Well-suited for sorting and searching.

Disadvantages of Array in C programming

Inflexible Size: Difficult to resize once created.

Slow Insertions/Deletions: Shifting elements is costly for large arrays.

Type Restrictions: Limited to hold elements of the same data type.

FAQs of Array in C