Alan Gauld <alan.ga...@btinternet.com> Wrote in message: > On 19/04/14 21:48, Vipul Sharma wrote: > >> *if a == 5 and b == 5:* >> * # do something* >> >> *if a == b and b == 5:* >> * # do something * >> >> which made me think, is there any difference between the two ? > > Yes. > I don't know how python actually does it but in a general > sense there is not much if any difference when the conditions > are true but if, for example, a is 5 and b is 4 then consider > what happens: > > a==5 and b==5 > 1) check if a==5 -> True > 2) check if b==5 -> False > 3) skip if block > > a==b and b==5 > 1) check if a == b -> False > 2) skip if block > > So the second version notionally does one less test for a > false condition. But its arguable less readable so do you > trade readability for a (marginal) speed improvement? >
You're right, the second expression is faster for 5,4. But the first is faster for 4,4. So choosing for speed depends on what you know about probable values. -- DaveA _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
