Thread: Weird behavior with &&

It's been awhile since I've worked with C, and I was playing around with some basic code to refresh, and I'm getting a weird result.

I've initialized a 2d array of dxd - let's say d = 4. Then using the following code, I just print it out, but do not want to print the bottom right corner.

Code:

for(int i = 0; i < d; i++) {
        for(int j = 0; j < d; j++) {
            if (i != (d - 1) && j != (d - 1)) {
                // printf("(i = %i and j = %i)", i, j);
                printf("%i  ", board[i][j]);
            }
        }
        printf("\n");
}

So instead of print out something like this:
15 14 13 12
11 10 9 8
7 6 5 4
3 1 2 _

I'm getting this:
15 14 13
11 10 9
7 6 5

I've looked over the loop several times and it seems correct. Am I wrong here?

You need to use OR, not AND. The code as written says to only print the element if neither of the indices are d - 1, so it doesn't print the last column or the last row.

You want to say "don't print the element if both indices are d - 1", basically something like:

Code:

if (i == d-1 && j == d-1)
    do nothing
else
    print the element

Since we don't generally want a branch of an if statement that does nothing, we can negate the condition:

Code:

if (!(i == d-1 && j == d-1))
    print the element

Using De Morgan's Laws we can express it as:

Code:

if (i != d-1 || j != d-1)
    print the element

Thanks everyone! For some reason my brain was telling me that statement evaluates to true when both were d - 1. I feel like such an idiot now