Random Exploration in Array c programming - c

Question

I have created an array full of letters and I'm stuck on implementing the function for the cell to randomly move in one of 8 directions (N, NE, E, SE, S, SW, W, NW). I've used a switch statement for the basic 4 direction but couldn't figure out the other 4 directions.
void randomStep()
{
if ((island[ro][co + 1] != ('B'||'L') || co == NUMROWS - 1 )&& (island[ro + 1][co] != ('B'||'L') || ro == NUMCOLS -1) && (island[ro - 1][co] != ('B'||'L') || ro == 0)
&& (island[ro][co - 1] != ('B'||'L') || co == 0))
break;
int direction = rand() % 8;
switch (direction) {
case 0: if (co < NUMROWS - 1 && island[ro][co + 1] == 'B'||'L'){ //move right
co++;
break;
}
case 1: if (ro < NUMCOLS -1 && island[co + 1][ro] == 'B'||'L') { //move down
ro++;
break;
}
case 2: if (ro > 0 && island[ro - 1][co] == 'B'||'L'){ //move up
ro--;
break;
}
case 3: if (co > 0 && island[ro][co - 1] == 'B'||'L') { //move left
co--;
break;
}

Answer 1

You can simply combine the conditions and results of two other cases. Here is an example for NW (left and up)
case 4: if (ro > 0 && co > 0 && island[ro - 1][co - 1] == 'B'||'L') { //move up & left
ro--;
co--;
}
break;
Note that I have moved the position of the break; to be outside the if code block.
I think you may also have an error with
... island[ro - 1][co - 1] == 'B'||'L' ...
which I guess should be
... island[ro - 1][co - 1] == 'B' || island[ro - 1][co - 1] == 'L' ...
and similarly in the other cases.

Answer 2

You can move parts of your code into functions:
bool mayGoUp(int ro, int co)
{
return ro > 0;
}
bool mayGoDown(int ro, int co)
{
return ro < NUMROWS - 1;
}
bool mayGoLeft(int ro, int co)
{
return co > 0;
}
bool mayGoRight(int ro, int co)
{
return co < NUMCOLS - 1;
}
Note: I changed the logic a bit: from co < NUMROWS - 1 to co < NUMCOLS - 1; not sure which one is the correct one.
Then you can combine them in a straightforward way:
bool mayGoUpLeft(int ro, int co)
{
return mayGoUp(ro, co) && mayGoLeft(ro, co);
}
Then, using them in your code will make your code clearer:
switch (direction) {
case 0:
if (MayGoRight(ro, co) && island[ro][co + 1] == ...
{ //move right
co++;
break;
}
...
case 99:
if (MayGoUpRight(ro, co) && ...
{ // move up and right
ro--;
co++;
break;
}