اكتب برنامج بلغة C لإيجاد مجموع العناصر المثلث السفلي لمصفوفة

/*Write a program in C to find the sum of lower triangular elements of a matrix*/

#include <stdio.h>
int main()
{
    int R, C, n, r, c, sum=0;
	int arr1[3][3]={{1, 2, 3},
				   {4, 5, 6},
				   {7, 8, 9}};
    R = C = n = 3;
	int i,j;
 //------------- print original array ------------------	
	printf("The given array is :  \n");
	for(i = 0; i < R; i++)
	{
	for (j=0;j<C;j++)
	{
	printf("%d  ", arr1[i][j]);
    } 
	printf("\n");
	}
//------------------------------------------------------ 	
 printf("The elements being summed of the lower triangular matrix are: ");	
    for(r = 0; r < R; r++)
	{
        for(c = 0; c < C; c++)
		{
            if(r > c)
			{
			    printf("%d  ",arr1[r][c]);
                sum += arr1[r][c];
            }
        }
    }
    printf("\nThe Sum of the lower triangular Matrix Elements are: %d", sum);
    return 0;
}