Why is goto considered harmful, and when might you actually use it?

Arbitrary goto jumps make control flow a tangle ("spaghetti code") — but one disciplined use survives: jumping forward to a single cleanup/error label.

Don't use goto like this:

c = 0, i = 0;
test:
    if (i >= N) goto end;
    c += a;
    i++;
    goto test;
end:

Use a loop instead:

for (i = 0; i < N; i++) {
    c += a;
}

When goto IS acceptable - error cleanup:

// Without goto - deeply nested, repetitive cleanup
void foo(int a, int N) {
    if (a) {
        if (b) {
            if (c) {
                do_something();
            } else undo_stuff();
        } else undo_stuff();
    } else undo_stuff();
}

// With goto - cleaner error handling
void foo(int a, int N) {
    if (!a) goto error;
    if (!b) goto error;
    if (!c) goto error;
    do_something();
    return;
error:
    undo_stuff();
}

The Linux kernel uses this pattern extensively for cleanup.

Go deeper:

• Goto — Wikipedia — Dijkstra's critique, spaghetti code, and structured programming.