I'm trying to parse a Fen String (char *starting_fen), but it doesn't seem to be working.

starting_fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

void init_board(char *starting_fen)
{
    int rank = 7, file = 0, fen_length = strlen(starting_fen);

    for (int i = 0; i < fen_length; i  )
    {
        if (starting_fen[i], "/") // <-- works for all characters?
        {
            printf("SYMBOL @ idx %d ==> '%c'\n", i, starting_fen[i]);
            // file = 0;
            // rank--;
        }
    }
}

This is my output:

SYMBOL @ idx 0 ==> 'r'
SYMBOL @ idx 1 ==> 'n'
SYMBOL @ idx 2 ==> 'b'

//...

SYMBOL @ idx 53 ==> '0'
SYMBOL @ idx 54 ==> ' '
SYMBOL @ idx 55 ==> '1'

I tried using strcmp (if (strcmp(starting_fen[i], "/"))) but got a Segmentation fault...

CodePudding user response：

I answer this because it is a funny bug. Here:

if (starting_fen[i], "/")

You are calling , operator. So it returns "/" which always will be evaluated to true (Since it is a address which will have a value not equal to 0). Your code need to be like this:

if (starting_fen[i] == '/')

So 2 changes:

1. You need == operator to check equality.
2. Characters are identified by ' not ".

CodePudding user response：

This fails:

if (starting_fen[i], "/") {

because starting_fen[i], "/" is always "/" which is not null. See the wikipdia page about the comma operator

This fails:

if (strcmp(starting_fen[i], "/")) {

Because starting_fen[i] will be a char, not a pointer to a string. Thus it will try to read a location in early memory and fail.

This fails:

if (starting_fen[i] == "/") {

Since you are trying to compare a char to a pointer.

This is correct:

if (starting_fen[i] == '/') {