I have submitted a new Ada example file, xt12a.adb and have made changes to x12a.adb according to the discussion several days ago about problems with emulating sprintf. I also made changes in x12a.adb so that it uses data structures from the thick binding rather than the thin binding. (See related note in another e-mail from me today.)
I think that it is generally not a good idea to make the Ada examples emulate C when there is an Ada way to get the job done. Those who are interested will see that rather than use sprintf and make Ada programmers (including this one 8^) scratch their heads, I used the 'Image function. Generally, if there is a type T and X is a value of T, there is a function T'Image(X) which returns a string representation of the name of X unless T is an Integer type in which case the returned string consists of the digits of X along with a leading minus sign if X is negative. Inversely, if S is a string containing a valid integer literal and T is an Integer type, then T'Value(S) is the numeric value of that literal. This is not used in this example, just FYI. String (and 1D array) concatenation is accomplished using the & operator but that is not necessary in this example either. Jerry On May 24, 2007, at 4:48 PM, Alan W. Irwin wrote: > On 2007-05-24 15:25-0600 Orion Poplawski wrote: > >> In plplot-5.7.3/examples/ada/x12a.adb, the sprintf function is >> declared >> and imported as follows: >> >> procedure Sprintf( buffer : out char_array; format : in >> char_array; >> variable: in PLFLT ); >> pragma Import(C, Sprintf, "sprintf" ); >> >> This is incorrect because sprintf's declaration is sprintf (char *, >> const char *, ...) (varargs) not sprintf (char *, const char *, >> float). >> This happens to work on i386 because of the ABI happens to be the >> same. It isn't on x86_64 and so crashes. See >> https://bugzilla.redhat.com/bugzilla/process_bug.cgi#c1 and the >> http://gcc.gnu.org/onlinedocs/gnat_ugn_unw/Calling- >> Conventions.html note >> about varargs for more info. >> >> If you really need to use sprintf you'll need to write a write a >> sprintff(char *, const char *, float) wrapper to sprintf and >> interface >> to that. Likewise for any other arguments used (currently just >> the one). >> >> Not sure if any plplot routines use varargs arguments, but if so the >> current ada imports are probably incorrect. > > Thanks, Orion, for your report. > > To answer Orion's last comment first, I looked in src/*.c for "..." > and there > doesn't seem to be any libplplot routines with a variable number of > arguments so I don't think that is going to be an issue. > > To answer Orion's second-last comment, I think we should look for > an Ada > alternative to Importing the C sprintf function because of the > difficulties > you have found with that method. Virtually every language has a > native way > to transform from integer, floating-point etc. representations, to > strings. > > Jerry, are you aware of the normal way to do this in Ada? N.B. > this has > nothing to do with API questions or our Ada interface and is merely a > question about how to transform from integer and floating point > representations to strings in Ada since that capability is needed for > the Ada implemention of example 12 and several other of our examples. > > Alan ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
