C# program to check if two matrices are identical

In C#, to check whether two matrices are identical, you need to compare their dimensions first and then their corresponding elements. Two matrices are considered identical if they have the same dimensions and all corresponding elements are equal.

Algorithm

The algorithm for checking matrix equality involves the following steps −

• Compare the dimensions (rows and columns) of both matrices

• If dimensions don't match, the matrices cannot be identical

• If dimensions match, compare each corresponding element

• Use a flag to track if all elements are equal

Syntax

Following is the basic syntax for matrix comparison −

if (rows1 != rows2 || cols1 != cols2) {
    // Matrices cannot be compared
} else {
    // Compare each element
    for (int i = 0; i < rows1; i++) {
        for (int j = 0; j < cols1; j++) {
            if (matrix1[i, j] != matrix2[i, j]) {
                // Matrices are not identical
            }
        }
    }
}

Using Predefined Matrices

Example

using System;

class MatrixComparison {
    public static void Main() {
        int[,] matrix1 = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };
        int[,] matrix2 = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };
        
        int rows1 = matrix1.GetLength(0);
        int cols1 = matrix1.GetLength(1);
        int rows2 = matrix2.GetLength(0);
        int cols2 = matrix2.GetLength(1);
        
        Console.WriteLine("Matrix 1:");
        DisplayMatrix(matrix1, rows1, cols1);
        
        Console.WriteLine("Matrix 2:");
        DisplayMatrix(matrix2, rows2, cols2);
        
        bool areIdentical = CheckMatrixEquality(matrix1, matrix2, rows1, cols1, rows2, cols2);
        
        if (areIdentical) {
            Console.WriteLine("The matrices are identical!");
        } else {
            Console.WriteLine("The matrices are not identical!");
        }
    }
    
    static bool CheckMatrixEquality(int[,] mat1, int[,] mat2, int r1, int c1, int r2, int c2) {
        if (r1 != r2 || c1 != c2) {
            Console.WriteLine("Matrices have different dimensions and cannot be compared.");
            return false;
        }
        
        for (int i = 0; i < r1; i++) {
            for (int j = 0; j < c1; j++) {
                if (mat1[i, j] != mat2[i, j]) {
                    return false;
                }
            }
        }
        return true;
    }
    
    static void DisplayMatrix(int[,] matrix, int rows, int cols) {
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                Console.Write(matrix[i, j] + " ");
            }
            Console.WriteLine();
        }
    }
}

The output of the above code is −

Matrix 1:
1 2 3 
4 5 6 
7 8 9 
Matrix 2:
1 2 3 
4 5 6 
7 8 9 
The matrices are identical!

Comparing Different Matrices

Example

using System;

class DifferentMatrices {
    public static void Main() {
        int[,] matrix1 = { {1, 2}, {3, 4} };
        int[,] matrix2 = { {1, 2}, {3, 5} };
        
        Console.WriteLine("Matrix 1:");
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                Console.Write(matrix1[i, j] + " ");
            }
            Console.WriteLine();
        }
        
        Console.WriteLine("Matrix 2:");
        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < 2; j++) {
                Console.Write(matrix2[i, j] + " ");
            }
            Console.WriteLine();
        }
        
        bool identical = true;
        for (int i = 0; i < 2 && identical; i++) {
            for (int j = 0; j < 2; j++) {
                if (matrix1[i, j] != matrix2[i, j]) {
                    identical = false;
                    Console.WriteLine($"Difference found at position [{i},{j}]: {matrix1[i, j]} != {matrix2[i, j]}");
                    break;
                }
            }
        }
        
        Console.WriteLine(identical ? "Matrices are identical!" : "Matrices are not identical!");
    }
}

The output of the above code is −

Matrix 1:
1 2 
3 4 
Matrix 2:
1 2 
3 5 
Difference found at position [1,1]: 4 != 5
Matrices are not identical!

Comparing Matrices with Different Dimensions

Example

using System;

class DifferentDimensions {
    public static void Main() {
        int[,] matrix1 = { {1, 2, 3}, {4, 5, 6} };  // 2x3 matrix
        int[,] matrix2 = { {1, 2}, {4, 5} };        // 2x2 matrix
        
        int rows1 = matrix1.GetLength(0);
        int cols1 = matrix1.GetLength(1);
        int rows2 = matrix2.GetLength(0);
        int cols2 = matrix2.GetLength(1);
        
        Console.WriteLine($"Matrix 1 dimensions: {rows1}x{cols1}");
        Console.WriteLine($"Matrix 2 dimensions: {rows2}x{cols2}");
        
        if (rows1 != rows2 || cols1 != cols2) {
            Console.WriteLine("Matrices have different dimensions and cannot be identical.");
        } else {
            Console.WriteLine("Matrices have same dimensions. Proceeding with element comparison...");
        }
    }
}

The output of the above code is −

Matrix 1 dimensions: 2x3
Matrix 2 dimensions: 2x2
Matrices have different dimensions and cannot be identical.

Key Points

• Dimension Check: Always verify that both matrices have the same number of rows and columns

• Element Comparison: Use nested loops to compare each corresponding element

• Early Exit: Use a flag or break statement to exit early when a mismatch is found

• GetLength() Method: Use GetLength(0) for rows and GetLength(1) for columns

Conclusion

Checking matrix equality in C# requires first comparing dimensions and then iterating through all elements to verify they match. Using a systematic approach with proper dimension validation ensures accurate comparison and prevents runtime errors when matrices have different sizes.