Thread: Using 2 sets of arrays for a random walk 2D program

I'm a beginner in C. I'm writing a program to demonstrate a random walk in 2D (that is, a point up/down/left/right, y+1, y-1, x-1, x+1 ). I have written a program that randomly generates numbers of up/down/left/right for me, however as I get to the distance travelled calculation part (distance = r = sqrt(x*x+y*y) ), I realise I better off do this with arrays.

I looked up some books and made a start by setting

Code:

int dx[]= { 0, 0, -1, 1 } ;
int dy[]= { -1, 1, 0, 0 } ;

but I am struggling on putting them together, and it is hard to find examples online on that.

Any help or suggestion is appreciated.Attachment 11040

Code:

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


int up;
int down;
int left;
int right;


int x = 0;
int y = 0;
int dx[]= { 0, 0, -1, 1 } ;
int dy[]= { -1, 1, 0, 0 } ;
int r;


int flip( void );
int main( void )
{
int toss;

srand(time(NULL));

FILE *out;
out=fopen("data.txt", "w");
for ( toss = 1; toss <= 200; toss++ ){
    printf( "%d\n", flip( ));
    fprintf(out,"%d\n",flip( ));


    if (flip( ) == 0)
    up++;
    else if (flip( ) == 1)
    down++;
    else if (flip () == 2)
    left++;
    else
    right++;


}
fclose(out);


printf( "Up had been flipped %d times\n", up );
printf( "Down had been flipped %d times\n", down );
printf( "Left had been flipped %d times\n", left );
printf( "Right had been flipped %d times\n", right );


return 0;

}
int flip( )
{
    int i = rand() % 4;


if (i == 0)
   return 0;

else if (i == 1)
return 1;

else if (i == 2)
return 2;

else
return 3;

}