> Ruben J=F6nsson schreef op 06-Apr-14 2:24 PM:
> > Regarding goto:
> >
> > Here is a piece of code from the demo app for the TCP/IP stack from Mic=
rochip:
> >
> >    ...
> >    // Read all browser POST data
> >    while(curHTTP.byteCount)
> >    {
> >      // Read a form field name
> >      if(HTTPReadPostName(curHTTP.data, 6) !=3D HTTP_READ_OK)
> >        goto ConfigFailure;
> > 		=09
> >      // Read a form field value
> >      if(HTTPReadPostValue(curHTTP.data + 6, sizeof(curHTTP.data)-6-2) !=
=3D
> > HTTP_READ_OK)
> >        goto ConfigFailure;
> >
> >      //some more test cases here which all jumps to ConfigFailure on fa=
ilure
> >    }
> >
> >    // do something if all is ok here
> >    return HTTP_IO_DONE
> > ConfigFaulure:
> >    // Do something else on failure here
> >    return HTTP_IO_DONE
> > }
> > 	=09
> > Of course this could be handled without goto but it seems like a good w=
ay to
> > handle this with a goto here. I guess it all depends on how the goto is=
 used.
> >
> >
>=20
> IMO this would be better written either
>=20
> - with the while and tests in one function, with 'return failure'=20
> instead of the goto's; call this function from another function, which=20
> does the 'postprocessing.
>=20
> or
>=20
> - with 'status =3D failure; break;' at the goto's, and a single if at the=
=20
> end which tests the status.
>=20
> Wouter

I am not sure that I agree that this would be better written in this case. =
The=20
first option makes the code harder to read since I have to go and look up t=
he=20
function to know what it is doing. I also have to pass along some variables=
=20
and/or pointers and of course calling the function which introduces overhea=
d on=20
the compiled code (not by much but still...).

I would probably use the second option myself, mostly because I have been=20
taught that goto is an evil statement in C. However, here it introduces one=
=20
more variable that has to be initialized, a break that could be forgotten (=
and=20
only discovered if all if statements are tested against a failure result). =
It=20
also makes the code harder to read since I have to go down and check what=20
happens after the break. break is actually just a goto anyway but with the=
=20
difference that it is not always obvious where it goes too or what it does.=
 A=20
goto with a meaningful label on the other hand...

I have now learned that goto is not an evil statement but it can be used in=
 an=20
evil way. There is actually a reason why it does exist.

I am not trying to convince you or anyone else to start using gotos in C bu=
t=20
just saying that sometimes it does make sense to do so and it may be the be=
st=20
option (such as in this case, in my opinion).

/Ruben


--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.