Interrupts and delay()

Using Arduino Programming Questions
5

Robin2:
What does this do

PORTB ^= (1 << PORTB0);

I can never get my head around that notation. Can you express the RHS as a binary value?

I'm wondering if bits are mangled in PORTB that should not be mangled.

...R

Toggles bit zero in PORTB, i.e. PORTB = PORTB ^ 0x01;

Shouldn't mangle any other bits.

Common idiom, worth mastering.

PS: But it is not an atomic operation, so if not executed with interrupts inhibited (as it is here by virtue of being in an ISR), it could cause unintended results.