rcs91900@zach.fit.edu ( Charles Stockman /ADVISOR-Clutterham) (04/06/91)
I am writing a C++ compiler and have one quick question
In C/C++ Octal is defined as
012 (octal) --> 10 (decimal)
Instead of starting octals off with a 0 I am planning to start them of with
0o
0o12 (octal) --> 10 (decimal)
The reason is that I want to make it easier to build the scanner. By using
0o all I would have to do is check for 0o and surely know if it was an
octal or not. In the Ansi standard either an octal or a floating digit
may start with a 0 so it would take longer to decide if it was an octal or
floating point and the code would not be as clean.
045 --> octal
0.3 --> floating point
Well --> What do you think, should I change it or keep it the same ?cs326ag@ux1.cso.uiuc.edu (Loren J. Rittle) (04/06/91)
In article <2264@winnie.fit.edu> rcs91900@zach.fit.edu ( Charles Stockman /ADVISOR-Clutterham) writes: >I am writing a C++ compiler and have one quick question > >In C/C++ Octal is defined as > > 012 (octal) --> 10 (decimal) > >Instead of starting octals off with a 0 I am planning to start them of with >0o > > 0o12 (octal) --> 10 (decimal) > >The reason is that I want to make it easier to build the scanner. By using >0o all I would have to do is check for 0o and surely know if it was an >octal or not. In the Ansi standard either an octal or a floating digit >may start with a 0 so it would take longer to decide if it was an octal or >floating point and the code would not be as clean. Unless you are designing an ad hoc scanner (i.e. you aren't using Lex and Yacc/Bison), the above is not true. If you *are* designing an ad hoc scanner, then I say you're crazy :-). Even if you are designing an ad hac scanner (you're still crazy), if it starts with 0[^.] then you know it is octal. Scanning for 0[^.] should be of the same complexity as scanning for 0o. In any event, I would not deviate from the standard... Put it is your project and you can take any short cuts you want... > 045 --> octal > 0.3 --> floating point > >Well --> What do you think, should I change it or keep it the same ? In sum, keep it the same. Loren J. Rittle -- ``NewTek stated that the Toaster *would* *not* be made to directly support the Mac, at this point Sculley stormed out of the booth...'' --- A scene at the recent MacExpo. Gee, you wouldn't think that an Apple Exec would be so worried about one little Amiga device... Loren J. Rittle l-rittle@uiuc.edu
ckp@grebyn.com (Checkpoint Technologies) (04/06/91)
In article <2264@winnie.fit.edu> rcs91900@zach.fit.edu ( Charles Stockman /ADVISOR-Clutterham) writes: >I am writing a C++ compiler and have one quick question >Instead of starting octals off with a 0 I am planning to start them of with >0o > 0o12 (octal) --> 10 (decimal) This is not a good idea. This makes your compiler unable to compile a great deal of existing code, so you shouldn't really call it C++. Of course, if you want to invent a new language, that's up to you! Then you could make all the arbitrary syntax decisions you want to. -- First comes the logo: C H E C K P O I N T T E C H N O L O G I E S / / ckp@grebyn.com \\ / / Then, the disclaimer: All expressed opinions are, indeed, opinions. \ / o Now for the witty part: I'm pink, therefore, I'm spam! \/
rkitts@netcom.COM (Rick Kitts) (04/07/91)
In article <2264@winnie.fit.edu> rcs91900@zach.fit.edu ( Charles Stockman /ADVISOR-Clutterham) writes: >I am writing a C++ compiler and have one quick question > >In C/C++ Octal is defined as > > 012 (octal) --> 10 (decimal) > >Instead of starting octals off with a 0 I am planning to start them of with >0o > > 0o12 (octal) --> 10 (decimal) > >The reason is that I want to make it easier to build the scanner. > [...] What type of scanner do you plan to build? I assume that you will be using a greedy algorithm, meaning that it will be a simple thing to check first that the constant starts with a 0 and that it does or does not contain a decimal point. I think that you might wish to re-examine your scanner design if this is in fact a real problem. >Well --> What do you think, should I change it or keep it the same ? Not using octal constants myself I really don't care very much. But I must tell you that a compiler would have to generate outrageously efficient code for me to purchase it if it did not conform to the standard.