floyds_triangle_bottom_right_corner_v1.c

/*

    floyds_triangle_bottom_right_corner_v1.c

    Task:
    https://web.facebook.com/photo.php?fbid=1802749856529188&set=pcb.1570362636455914&type=3&theater&ifg=1

    https://www.tutorialspoint.com/c_standard_library/c_function_atoi.htm

    https://www.tutorialspoint.com/c_standard_library/c_function_isdigit.htm


    You can find all my C programs at Dragan Milicev's pastebin:

    https://pastebin.com/u/dmilicev

*/

#include <stdio.h>
#include <stdlib.h>     // for atoi()
#include <ctype.h>      // for isdigit()


void make_triangle_flipped( int arr[], int n )
{
    int i=0;                            // index of array elements
    int r=0, c=0;                       // row and column of matrix
    int number=n*(n+1)/2, num_of_zeros=-1;
    int j;                              // iterator for loop

    printf("\n\t n = %d \n\n", n);

    for(r=0; r<n; r++)                  // for all rows of matrix
    {
        num_of_zeros++;
        for(j=0; j<num_of_zeros; j++)   // put zeros
            arr[i++]=0;

        for(j=num_of_zeros; j<n; j++)   // put numbers
            arr[i++]=number--;
    }
}

void print_array_as_square_matrix( int arr[], int n )
{
    int i=0,r,c;                        // r is row, c is column

    printf("\n");

    for(r=0; r<n; r++)
    {
        for(c=0; c<n; c++)
        {
            printf("%4d", arr[i++]);
        }
        printf("\n\n");                 // new line for new row
    }
}


int main(int argc, char *argv[])
{
    int n;
    int arr[1000];

    if( argc != 2 ){    // if there is no only one command line argument

        printf( "\n Do not forget first to compile this program \n"
                "\n and then run exe file from command line \n"
                "\n exactly with quotes, like this: \n\n"
                "\n \"floyds_triangle_top_right_corner_v1.exe\" 6 \n\n" );

        printf("\n\n Press any key to exit. \n");
        _getch();       // to pause the screen
        return 1;       // exit because there is no command line arguments
    }

    n = atoi( argv[1] );

    if( isdigit(n) || n<2 || n>20 )
    {
        printf("\n Argument of program must be an integer greater than 1 and less than 21 ! \n");
        printf("\n\n Press any key to exit. \n");
        _getch();       // to pause the screen
        return 1;       // exit because argument is not valid integer
    }

    make_triangle_flipped( arr, n );
    print_array_as_square_matrix( arr, n );

    _getch();           // to pause the screen
    return 0;

} // main()