2-D Array in C

In C programming, a 2D array, also known as a two-dimensional array, is a collection of elements organized in a grid-like structure with rows and columns. It is a matrix-like data structure where elements are accessed using two indices: one for the row and one for the column.

To declare and use a 2D array in C, you typically follow these steps:

1. Array Declaration:

• Specify the data type of the elements in the array.
• Provide a name for the array.
• Use square brackets `[][]` to indicate that it is a 2D array.
• Specify the size of the array by indicating the number of rows and columns it should have.
Syntax:

data_type array_name[rows][columns];

Example

int matrix[3][4];  // Declaration of a 2D integer array with 3 rows and 4 columns
float table[2][2];  // Declaration of a 2D float array with 2 rows and 2 columns

2. Array Initialization (optional)

• Assign initial values to the elements of the array.
• This step is not mandatory. If not initialized explicitly, the elements will have default values (e.g., 0 for integers, 0.0 for floats, NULL for pointers).

Syntax

data_type array_name[rows][columns] = {
    {value1, value2, ...},
    {value1, value2, ...},
    ...
};

Example

int matrix[3][4] = {
    {1, 2, 3, 4},
    {5, 6, 7, 8},
    {9, 10, 11, 12}
};  // Initialization of a 2D integer array

float table[2][2] = {
    {1.5, 2.3},
    {3.7, 4.2}
};  // Initialization of a 2D float array

3. Array Access

• Access individual elements of the array using their row and column indices.
• Indices start from 0 and go up to `rows - 1` for the row index and `columns - 1` for the column index.

Syntax

array_name[row_index][column_index]

Example

int value = matrix[1][2];  // Accessing the element in the 2nd row and 3rd column
printf("%d\n", value);  // Output: 7

matrix[2][1] = 15;  // Modifying the element in the 3rd row and 2nd column

4. Array Iteration

• Use nested loops (e.g., two `for` loops) to iterate over the 2D array elements.
• The outer loop controls the row index, and the inner loop controls the column index.
• Access each element using its row and column indices within the loop body.

Example

for (int i = 0; i < 3; i++) {
    for (int j = 0; j < 4; j++) {
        printf("%d ", matrix[i][j]);
    }
    printf("\n");
}

2D arrays are commonly used to represent matrices, tables, grids, and other tabular structures in C. They provide a convenient way to store and process data organized in rows and