[jlalt]

small letter for non optional parameter, capital letter for optional parameter which need to specif a default value for it too.
so if you wanna use S you gotta assign default value and a size.
default value inside () size inside []

so now we get that, your D needs a default value.

->

PHP код:

if(sscanf(params, "s[32]dD(-1)", choice, id, amount))