scrolling through http://git.suckless.org/st/plain/st.c I stumbled upon
#define LEN(a) (sizeof(a) / sizeof(a)[0]) I know precompiler magic is hard, and my C aint the best
but it makes me wonder if the parens at the end make sense - shouldn't it be something like
#define LEN(a) (sizeof(a) / sizeof((a)[0])) The sizeof operator doesn't really need parenthesis when the operand is a left-side expression instead of a type, so your parenthesis at the second sizeof are not needed, as this one doesn't expect a type (because of the trailing [0]). This LEN macro seems to be used to get the size of a statically defined vector.
For example:
int v[10]; LEN(v) will expand to (sizeof(v)/sizeof(v)[0]) And (v)[0] is the same as v[0] so the second sizeof is actually something like sizeof v[0] which is valid use of sizeof (no parenthesis needed)
A well-known (at least here at Stack Overflow) example of a sizeof that doesn't needing parenthesis is:
int *v; v=malloc(10*sizeof *v); To get a dynamically defined 10 element vector. Note that the previous LEN macro won't work here.
