Data Structures 11 - Two-Dimensional Arrays and Matrix Multiplication

Code

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

#define ROWS 4       // Define number of rows as 4
#define COLUMNS 5    // Define number of columns as 5

// Define dynamic two-dimensional array structure
typedef struct TwoDArray{
	int rows;        // Number of rows
	int columns;     // Number of columns
	int** elements;  // Element pointer, pointing to the two-dimensional array
} TwoDArray, *TwoDArrayPtr;

// Define static two-dimensional array structure
typedef struct TwoDStaticArray{
	int rows;         // Number of rows
	int columns;      // Number of columns
	int elements[ROWS][COLUMNS];  // Define static two-dimensional array
} TwoDStaticArray, *TwoDStaticArrayPtr;

// Initialize a dynamic two-dimensional array
TwoDArrayPtr initTwoDArray(int paraRows, int paraColumns){
	int i;
	TwoDArrayPtr resultPtr = (TwoDArrayPtr)malloc(sizeof(struct TwoDArray));  // Allocate memory for the structure
	resultPtr->rows = paraRows;        // Initialize number of rows
	resultPtr->columns = paraColumns;  // Initialize number of columns
	resultPtr->elements = (int**)malloc(paraRows * sizeof(int*));  // Allocate memory for row pointer array
	for (i = 0; i < paraRows; i ++){
		resultPtr->elements[i] = (int*)malloc(paraColumns * sizeof(int));  // Allocate memory for each row's column elements
	}
 
	return resultPtr;  // Return pointer
}

// Randomly fill a two-dimensional array
void randomizeTwoDArray(TwoDArrayPtr paraPtr, int paraLowerBound, int paraUpperBound){
	int i, j;	
	for (i = 0; i < paraPtr->rows; i ++){
		for (j = 0; j < paraPtr->columns; j ++) {
			paraPtr->elements[i][j] = rand() % (paraUpperBound - paraLowerBound) + paraLowerBound;  // Generate random numbers to fill the array
		}
	}
}

// Print a two-dimensional array
void printTwoDArray(TwoDArrayPtr paraPtr){
	int i, j;	
	for (i = 0; i < paraPtr->rows; i ++){
		for (j = 0; j < paraPtr->columns; j ++) {
			printf("%d, ", paraPtr->elements[i][j]);  // Print element
		}
		printf("\r\n");  // Newline
	}
}

// Matrix multiplication
TwoDArrayPtr matrixMultiply(TwoDArrayPtr paraPtr1, TwoDArrayPtr paraPtr2){
	int i, j, k, sum;
	if (paraPtr1->columns != paraPtr2->rows){
		printf("Matrices cannot be multiplied.\r\n");  // Check if matrices can be multiplied
		return NULL;
	}
 
	TwoDArrayPtr resultPtr = initTwoDArray(paraPtr1->rows, paraPtr2->columns);  // Initialize result matrix
 
	for (i = 0; i < paraPtr1->rows; i ++){
		for (j = 0; j < paraPtr2->columns; j ++) {
			sum = 0;
			for (k = 0; k < paraPtr1->columns; k ++) {
				sum += paraPtr1->elements[i][k] * paraPtr2->elements[k][j];  // Calculate product and accumulate
			}
			resultPtr->elements[i][j] = sum;  // Store result
			printf("sum = %d, ", sum);  // Print partial result
		}
	}
 
	return resultPtr;  // Return result matrix
}

// Test function
void twoDArrayTest(){
	TwoDArrayPtr tempPtr1, tempPtr2, tempPtr3;
	tempPtr1 = initTwoDArray(3, 2);  // Initialize first matrix
	randomizeTwoDArray(tempPtr1, 1, 5);  // Randomly fill first matrix
	printf("The first matrix:\r\n");
	printTwoDArray(tempPtr1);  // Print first matrix
 
	tempPtr2 = initTwoDArray(2, 4);  // Initialize second matrix
	randomizeTwoDArray(tempPtr2, 4, 9);  // Randomly fill second matrix
	printf("The second matrix:\r\n");
	printTwoDArray(tempPtr2);  // Print second matrix
 
	tempPtr3 = matrixMultiply(tempPtr1, tempPtr2);  // Multiply matrices
	printf("The result:\r\n");
	printTwoDArray(tempPtr3);  // Print result matrix
}

// Initialize a static two-dimensional array
TwoDStaticArrayPtr initTwoDStaticArray(){
	int i, j;
	TwoDStaticArrayPtr resultPtr = (TwoDStaticArrayPtr)malloc(sizeof(struct TwoDStaticArray));  // Allocate memory for the structure
	resultPtr->rows = ROWS;        // Initialize number of rows
	resultPtr->columns = COLUMNS;  // Initialize number of columns
	for (i = 0; i < ROWS; i ++){
		for (j = 0; j < COLUMNS; j ++) {
			resultPtr->elements[i][j] = i * 10 + j;  // Fill elements
			
			printf("(%d, %d): %d; ", i, j, &(resultPtr->elements[i][j]));  // Print element and its address
		}
	}
	
	return resultPtr;  // Return pointer
}

// Main function
int main(){
	twoDArrayTest();  // Call test function
	TwoDStaticArrayPtr tempPtr = initTwoDStaticArray();  // Initialize static two-dimensional array
 
	return 1;  // Return 1
}

Code Summary

This code defines and implements several operations on two-dimensional arrays. It mainly includes initialization, random filling, printing, and matrix multiplication for both dynamic and static two-dimensional arrays. Here is a detailed summary:

1. Structure definitions:

   • TwoDArray: Used to represent a dynamic two-dimensional array, including row count, column count, and element pointer.
   • TwoDStaticArray: Used to represent a static two-dimensional array, including row count, column count, and element array.

2. Initialize dynamic two-dimensional array:

   • The initTwoDArray function allocates memory and initializes the row count, column count, and elements of the dynamic two-dimensional array.

3. Randomly fill the array:

   • The randomizeTwoDArray function randomly assigns each element of the two-dimensional array a value within a specified range.

4. Print the array:

   • The printTwoDArray function prints each element of the two-dimensional array row by row.

5. Matrix multiplication:

   • The matrixMultiply function performs matrix multiplication on two matrices and returns the result matrix. If the matrices cannot be multiplied, the function prints an error message.

6. Test function:

   • The twoDArrayTest function demonstrates initialization, random filling, printing, and matrix multiplication operations.

7. Initialize static two-dimensional array:

   • The initTwoDStaticArray function initializes a fixed-size static two-dimensional array and prints its elements and addresses.

8. Main function:

   • The main function calls the twoDArrayTest test function for dynamic two-dimensional arrays and initializes a static two-dimensional array.

Running Result

The first matrix:
4, 3, 
2, 4, 
2, 4, 
The second matrix:
5, 6, 8, 5, 
6, 6, 4, 8, 
sum = 38, sum = 42, sum = 44, sum = 44, sum = 34, sum = 36, sum = 32, sum = 42, sum = 34, sum = 36, sum = 32, sum = 42, The result:
38, 42, 44, 44, 
34, 36, 32, 42, 
34, 36, 32, 42, 
(0, 0): -810461064; (0, 1): -810461060; (0, 2): -810461056; (0, 3): -810461052; (0, 4): -810461048; (1, 0): -810461044; (1, 1): -810461040; (1, 2): -810461036; (1, 3): -810461032; (1, 4): -810461028; (2, 0): -810461024; (2, 1): -810461020; (2, 2): -810461016; (2, 3): -810461012; (2, 4): -810461008; (3, 0): -810461004; (3, 1): -810461000; (3, 2): -810460996; (3, 3): -810460992; (3, 4): -810460988;