Multidimensional Arrays in C

Multidimensional Arrays (C)

• Multidimensional arrays are arrays of arrays. Arrays can have many dimensions, but the most common are two-dimensional arrays (2D).
• A 2D array is like a matrix (table). Rows and columns are used to define positions in the array.
• Example: int matrix[2][3] = {{1, 4, 2}, {3, 6, 8}}
• The first dimension (e.g., [2]) represents the number of rows; the second ([3]) the number of columns.
• Values are stored in row-major order.

Two-Dimensional Array Initialization

• Two methods exist for array initialization:

  • Method 1: int multi_dim[4][3] = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120};
  • Method 2: int multi_dim[4][3] = {{10, 20, 30}, {40, 50, 60}, {70, 80, 90}, {100, 110, 120}};

• Both methods are valid . Method 2 is more readable and efficient for declaring 2D arrays.

Accessing Elements in a 2D Array

• To access an element within a 2D array, you specify the row index and column index within square brackets, e.g., name_of_the_array[row_index][column_index].

• Example: printf("%d", matrix[0][2]); - This would output 2.

Changing Array Elements

• Changing a value in a 2D array requires knowing the specific array element index. Example: matrix[0][0] = 9;

Looping Through 2D Arrays

• Iterating over a 2D array requires using nested for loops, one for each dimension.
• Example:

#include <stdio.h>
int main() {
    int matrix[2][3] = {{1, 4, 2}, {3, 6, 8}};
    int i, j;
    for (i = 0; i < 2; i++) {
        for (j = 0; j < 3; j++) {
            printf("%d\n", matrix[i][j]);
        }
    }
    return 0;
}

Example of Average Calculation

• Calculating average values can involve using a loop to sum then divide based on index to calculate the average value for a particular row or column.

  • Example:

int sum = 0;
for (int col = 0; col <= 3; col++) {
sum += rating[2][col];
}
double average = (double) sum / 4; 

• This example sums the elements in row 2 and then calculates the average rating by row 2.

Examples of Printing Matrices in Row and Column format

• Matrix rows and columns can be displayed using formatted output.
• An example is provided to show the output.

Example of Matrix Multiplication

• To multiply two matrices, you need to use nested loops.
• The inner loop calculates each element in the result matrix.

This quiz covers the basics of multidimensional arrays in C, focusing particularly on two-dimensional arrays. You'll learn about initialization methods, accessing elements, and how to represent data in a matrix form. Test your understanding of these concepts and enhance your programming skills.