non printing characters
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From: e p chandler on 5 Jul 2010 16:46 Someone sent me a program fragment to look at. It appears frequently in programs that he encounters. [typeless octal constants as bit patterns] character*1 ff,lf,cr /"014,"012,"015/ Yes, I know that combining a declaration with a data statment like this is non-standard. Aside from using the Fortran 95 (some compilers don't support it): character :: ff=achar(12),lf=achar(10),cr=achar(13) or replacing each ff, lf and cr in the program text with the appropriate achar(), is there a decent way of initializing these non-printing characters in a DATA statement? I don't particularly want to use Unix style character escapes. (\f , \n, \r). Elliot
From: Richard Maine on 5 Jul 2010 18:04 e p chandler <epc8(a)juno.com> wrote: > character*1 ff,lf,cr /"014,"012,"015/ > > Yes, I know that combining a declaration with a data statment like this is > non-standard. > > Aside from using the Fortran 95 (some compilers don't support it): > > character :: ff=achar(12),lf=achar(10),cr=achar(13) > > or replacing each ff, lf and cr in the program text with the appropriate > achar(), is there a decent way of initializing these non-printing characters > in a DATA statement? > > I don't particularly want to use Unix style character escapes. (\f , \n, > \r). I might suggest that you could use better compilers, and I'm slightly curious what compilers you are using that have trouble with this. If you said exactly what it was that the compiler objected to, it would be easier to suggest a workaround. As it is, I can't tell whether it is the achar intrinsic, the use of functions in initialization expressions, the f90 style initializer, or what. I suppose f77 compilers would be a problem. And I seem to recall, though not for sure, that F might disallow achar in favor of char. Those backslash escape things aren't at all portable anyway. If you have an f77 compiler that doesn't support achar, you could use char instead. In theory, it isn't as universal, but it should be a lot more portable than things like backslash escapes (and that initial syntax you showed is fairly rare). It is true that you can't use either char or achar in a DATA statement. As a last resort, you can set a variable value using an executable assignment statement (and achar or char) that is executed during program startup. -- Richard Maine | Good judgment comes from experience; email: last name at domain . net | experience comes from bad judgment. domain: summertriangle | -- Mark Twain
From: e p chandler on 5 Jul 2010 20:41 >>"Richard Maine" wrote >e p chandler wrote: > >> character*1 ff,lf,cr /"014,"012,"015/ >> >> Yes, I know that combining a declaration with a data statment like this >> is >> non-standard. >> >> Aside from using the Fortran 95 (some compilers don't support it): >> >> character :: ff=achar(12),lf=achar(10),cr=achar(13) >> >> or replacing each ff, lf and cr in the program text with the appropriate >> achar(), is there a decent way of initializing these non-printing >> characters >> in a DATA statement? >> >> I don't particularly want to use Unix style character escapes. (\f , \n, >> \r). > I might suggest that you could use better compilers, and I'm slightly > curious what compilers you are using that have trouble with this. If you > said exactly what it was that the compiler objected to, it would be > easier to suggest a workaround. As it is, I can't tell whether it is the > achar intrinsic, the use of functions in initialization expressions, the > f90 style initializer, or what. I suppose f77 compilers would be a > problem. And I seem to recall, though not for sure, that F might > disallow achar in favor of char. I made the mistake of suspecting but not testing. I thought that DVF 5.0 had a problem with initialization expressions. It compiles the statement above with no problem. But it does not allow C:\Users\epc\temp>df vv.f90 DIGITAL Visual Fortran Optimizing Compiler Version: V5.0 Copyright (c) 1997 Digital Equipment Corp. All rights reserved. vv.f90 vv.f90(1) : Error: This intrinsic function is invalid in constant expressions. [ATAN] real :: pi=4.0*atan(1.0) ---------------^ vv.f90(1) : Error: This is not a valid initialization expression. real :: pi=4.0*atan(1.0) --------------^ I thought erroneously that the compiler does not allow intrinsic functions there. So I'm sorry about leading you down the wrong path [snip] As you say, achar and char are not allowed inside of data statements. I actually asked the question from the point of view of someone who is stuck with a load of old programs that do use these octal literals in this way. Thanks -- Elliot
From: Richard Maine on 5 Jul 2010 21:42 e p chandler <epc8(a)juno.com> wrote: > I thought erroneously that the compiler does not allow intrinsic functions > there. It depends on the particular intrinsic function. The list of intrinsic functions allowed in initialization expressions by the standard has been gradually increasing over time (and particular compilers have sometimes allowed more than the standard). -- Richard Maine | Good judgment comes from experience; email: last name at domain . net | experience comes from bad judgment. domain: summertriangle | -- Mark Twain
From: Tobias Burnus on 6 Jul 2010 01:20
e p chandler wrote: > vv.f90(1) : Error: This is not a valid initialization expression. > real :: pi=4.0*atan(1.0) > --------------^ Using ATAN in initialization expressions is allowed since Fortran 2003, which one cannot expect from a "(c) 1997" compiler. Tobias |