Trash output in 8x8x2 array in C - c

Question

I'm trying to represent a 8x8 Cartesian plane whose contents would be a string of length 2. I'd like to keep as type-safety as I can this scheme and doing this:
typedef char cartesian[8][8][2];
cartesian xy;
for(int i=0; i<8; i++){
for(int j=0; j<8; j++){
xy[i][j][0] = ' '
xy[i][j][1] = ' '
}
}
// The first element would represent some kind of information, and the other one
// would be just elements like '+' or '*'. In other cases, this would be 'EMPTY',
// it means a double space.
xy[2][4][0] = 'B';
xy[2][4][1] = '+';
// The right printing method (cause it doesn't have any trash) would be:
for(int i=0; i<8; i++){
for(int j=0; j<8; j++){
printf("| %c%c ", xy[i][j][0], xy[I][j][1] );
}
printf("|\n");
}
But here's the question: Why the output trash with printf("| %s ", xy[i][j][]); ?
I know this could be a dumb question, but I'm out and tired now.
Thanks in advance.
By the way, doesn't work to assign. I mean: xy[2][4][] = "B+";.

Answer 1

Here is your code rewritten. Note that cartesian is now [8][8][3] and strcpy is used to fill the last array dimension. For clarity, I moved to clearing on xy into a separate function.
#include <stdio.h>
#include <string.h>
typedef char cartesian[8][8][3];
void clearXY(cartesian *xy)
{
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
strcpy((*xy)[i][j], " ");
}
}
}
int main(int argc, char *argv[])
{
cartesian xy;
// The first element would represent some kind of information, and the other one
// would be just elements like '+' or '*'. In other cases, this would be 'EMPTY',
// it means a double space.
clearXY(&xy);
strcpy(xy[2][4], "B+");
printf("-------- Method 1 --------\n");
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
printf("| %c%c ", xy[i][j][0], xy[i][j][1]);
}
printf("|\n");
}
printf("-------- Method 2 --------\n");
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
printf("| %s ", xy[i][j]);
}
printf("|\n");
}
printf("-------- Done ------------\n");
}