Messages in this thread | | | Date | Thu, 10 Jan 2019 22:44:08 +0300 | From | Dan Carpenter <> | Subject | Re: [PATCH] staging: vboxvideo: vbox_main: Remove unnecessary local variable |
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On Thu, Jan 10, 2019 at 05:00:24PM +0000, Sidong Yang wrote: > I think you just point out that my code isn't obvious because the > function returns negative error codes. I agree with you. But what if > change my code like if(hgsmi_query_conf() != 0). >
That's even worse! :P
You should do comparisons with zero when you are talking about zero meaning the number zero. In this case, hgsmi_query_conf() returns "zezro meaning success" not "zero meaning the number zero". How many bytes? Zero. That is the number zero.
!= zero is a double negative, because NOT and ZERO are negatives. If double negatives simplified the code we would add four of them instead of just the one:
if ((((hgsmi_query_conf() != 0) != 0) != 0) != 0) {
See? Adding != 0 doesn't make it simpler...
The other place where != 0 is appropriate besides talking about the number is when you're using a strcmp() function because it works like this:
if (strcmp(a, b) < 0) { <-- means a < b if (strcmp(a, b) == 0) { <-- means a == b if (strcmp(a, b) != 0) { <-- means a != b
regards, dan carpenter
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