programming-examples/c-sharp/Arrays/C# Sharp for multiplication of two square Matrices.cs

using System;
public class Exercise21
{
    public static void Main()
    {
        int i,j,k,r1,c1,r2,c2,sum=0;
        int[,] arr1 = new int[50,50];
        int[,] brr1 = new int[50,50];
        int[,] crr1 = new int[50,50];
        Console.Write("\n\nMultiplication of two Matrices\n");
        Console.Write("----------------------------------\n");
        Console.Write("\nInput the number of rows and columns of the first matrix :\n");
        Console.Write("Rows : ");
        r1 = Convert.ToInt32(Console.ReadLine());
        Console.Write("Columns : ");
        c1 = Convert.ToInt32(Console.ReadLine());
        Console.Write("\nInput the number of rows of the second matrix :\n");
        Console.Write("Rows : ");
        r2 = Convert.ToInt32(Console.ReadLine());
        Console.Write("Columns : ");
        c2 = Convert.ToInt32(Console.ReadLine());
        if(c1!=r2)
            {
                Console.Write("Mutiplication of Matrix is not possible.");
                Console.Write("\nColumn of first matrix and row of second matrix must be same.");
            }
        else
            {
                Console.Write("Input elements in the first matrix :\n");
                for(i=0; i<r1; i++)
                    {
                        for(j=0; j<c1; j++)
                            {
                                Console.Write("element - [{0}],[{1}] : ",i,j);
                                arr1[i,j] = Convert.ToInt32(Console.ReadLine());
                            }
                    }
                Console.Write("Input elements in the second matrix :\n");
                for(i=0; i<r2; i++)
                    {
                        for(j=0; j<c2; j++)
                            {
                                Console.Write("element - [{0}],[{1}] : ",i,j);
                                brr1[i,j] = Convert.ToInt32(Console.ReadLine());
                            }
                    }
                Console.Write("\nThe First matrix is :\n");
                for(i=0; i<r1; i++)
                    {
                        Console.Write("\n");
                        for(j=0; j<c1; j++)
                            Console.Write("{0}\t",arr1[i,j]);
                    }
                Console.Write("\nThe Second matrix is :\n");
                for(i=0; i<r2; i++)
                    {
                        Console.Write("\n");
                        for(j=0; j<c2; j++)
                            Console.Write("{0}\t",brr1[i,j]);
                    }
//multiplication of matrix
                for(i=0; i<r1; i++)
                    for(j=0; j<c2; j++)
                        crr1[i,j]=0;
                for(i=0; i<r1; i++)  //row of first matrix
                    {
                        for(j=0; j<c2; j++)  //column of second matrix
                            {
                                sum=0;
                                for(k=0; k<c1; k++)
                                    sum=sum+arr1[i,k]*brr1[k,j];
                                crr1[i,j]=sum;
                            }
                    }
                Console.Write("\nThe multiplication of two matrix is : \n");
                for(i=0; i<r1; i++)
                    {
                        Console.Write("\n");
                        for(j=0; j<c2; j++)
                            {
                                Console.Write("{0}\t",crr1[i,j]);
                            }
                    }
            }
        Console.Write("\n\n");
    }
}