fortran, Calling Fortran 77 dll's from Visual Basic under Excel

Calling Fortran 77 dll's from Visual Basic under Excel

Author	Message
Antonie Kot #1 / 7	Calling Fortran 77 dll's from Visual Basic under Excel Hi all I am using Absoft fortran 77 to create DLL's and I then call them from VBA under Excel97. I have been doing this for quite some time now. I have no trouble in sending variables of doubles and integers OR arrays of integers or doubles through to the DLL's. STRINGS, however, seems to be a problem. I have never send a string through to a DLL and this now stumbles me. I tried various ways. I declare the string in VBA as for instance Byval StringVar as String I then dimension the string to be a fixed length like Dim StringVar as String8 or Static StringVar as String8 On the Fortran side I then have STDCALL subroutine test(....., StringVar,...) character8 stringvar This does not work. What is wrong?? I also tried to have STDCALL subroutine test(....., StringVar,...) character() stringvar in my fortran code. It still does not work. The whole program is working fine because if I do not send a string through, i.e., if I make stringvar to be a double and I just work with stringvar as a real8 then the program works 100%. But, the program would be a bit more efficient if I could send a string through. How?. If anyone can help, please let me know. Thanks Antonie Kotze
Wed, 18 Jun 1902 08:00:00 GMT

Matt Carlto #2 / 7	Calling Fortran 77 dll's from Visual Basic under Excel I don't know much about Fortran 77 but I seem to remember from my Fortran 90 days strings need to be passed null terminated this can be acheived in VB by somthing like the following: Dim StringVar as String '''''''''''''''''''''''''''''''''''''''''''' 'Before the API call StringVar = StringVar & Chr(0) '''''''''''''''''''''''''''''''''''''''''''''' Call test(....., StringVar,...) I haven't tested this but I hope it works for you. Matt Quote: >Hi all >I am using Absoft Fortran 77 to create DLL's and I then call them from >VBA under Excel97. I have been doing this for quite some time now. >I have no trouble in sending variables of doubles and integers OR arrays of >integers or doubles through to the DLL's. >STRINGS, however, seems to be a problem. I have never send a string through to >a DLL and this now stumbles me. >I tried various ways. I declare the string in VBA as for instance >Byval StringVar as String >I then dimension the string to be a fixed length like >Dim StringVar as String8 >or >Static StringVar as String8 >On the Fortran side I then have > STDCALL subroutine test(....., StringVar,...) > character8 stringvar >This does not work. What is wrong?? >I also tried to have > STDCALL subroutine test(....., StringVar,...) > character() stringvar >in my fortran code. It still does not work. >The whole program is working fine because if I do not send a string through, >i.e., if I make stringvar to be a double and I just work with stringvar as a >real8 then the program works 100%. >But, the program would be a bit more efficient if I could send a string >through. >How?. >If anyone can help, please let me know. >Thanks >Antonie Kotze
Wed, 18 Jun 1902 08:00:00 GMT

Paul McEnte #3 / 7	Calling Fortran 77 dll's from Visual Basic under Excel I had this problem about a year and a half ago with F90 and eventually had to give up on using strings. Then someone mentioned using structures might be the solution but I never got to try it. Quote: > Hi all > I am using Absoft Fortran 77 to create DLL's and I then call them from > VBA under Excel97. I have been doing this for quite some time now. > I have no trouble in sending variables of doubles and integers OR arrays of > integers or doubles through to the DLL's. > STRINGS, however, seems to be a problem. I have never send a string through to > a DLL and this now stumbles me. > I tried various ways. I declare the string in VBA as for instance > Byval StringVar as String > I then dimension the string to be a fixed length like > Dim StringVar as String8 > or > Static StringVar as String8 > On the Fortran side I then have > STDCALL subroutine test(....., StringVar,...) > character8 stringvar > This does not work. What is wrong?? > I also tried to have > STDCALL subroutine test(....., StringVar,...) > character() stringvar > in my fortran code. It still does not work. > The whole program is working fine because if I do not send a string through, > i.e., if I make stringvar to be a double and I just work with stringvar as a > real8 then the program works 100%. > But, the program would be a bit more efficient if I could send a string > through. > How?. > If anyone can help, please let me know. > Thanks > Antonie Kotze
Wed, 18 Jun 1902 08:00:00 GMT

Marco A. Garci #4 / 7	Calling Fortran 77 dll's from Visual Basic under Excel When passing strings from VB to Fortran, you need to keep in mind that VB stores strings as BStrings. This format is basically not compatible with the one used by Fortran. BStrings are wide strings (i.e. each character takes 2 bytes), they are null terminated (actually double-null terminated), and have the length of the string right in front. A pointer to a bstring points to the first character of the string. As a rule, BStrings should only be modified through the supplied OLE-API, so you are not supposed to change a Bstring from inside Fortran (unless you do it calling the appropriate OLE-API). Now, the trick to pass BStrings from VB to Fortran is to do it by value. In the VB end, you declare the Fortran sub as: MyText As String) on the Fortran end, you declare the subroutine as stdcall subroutine MyStringSub(StringPtr) character(len=255) MyString pointer (StringPtr, MyString) : : You must make sure that MyString is long enough for the strings you are passing. Also, MyString will be null terminated, so you have to scan the string to find its length. This trick works because VB will convert the passed Bstring into a Multibyte string when calling API functions by Value. So what you get in your Fortran side is basically a pointer to a normal C-style string. For those of you that have been struggling with this problem, you should visit our web pages in about two more weeks. We will publish a library of subroutines (actually, a portion of our f90ADO library) that will allow passing bstrings back and forth between Fortran and VB. Marco A. Garcia Canaima Software 3981 Utah St. San Diego, CA 92104 U.S.A. http://www.canaimasoft.com Developers of f90SQL and f90ADO, the Complete Database Connectivity Solution for Fortran Quote: >Hi all >I am using Absoft Fortran 77 to create DLL's and I then call them from >VBA under Excel97. I have been doing this for quite some time now. >I have no trouble in sending variables of doubles and integers OR arrays of >integers or doubles through to the DLL's. >STRINGS, however, seems to be a problem. I have never send a string through to >a DLL and this now stumbles me. >I tried various ways. I declare the string in VBA as for instance >Byval StringVar as String >I then dimension the string to be a fixed length like >Dim StringVar as String8 >or >Static StringVar as String8 >On the Fortran side I then have > STDCALL subroutine test(....., StringVar,...) > character8 stringvar >This does not work. What is wrong?? >I also tried to have > STDCALL subroutine test(....., StringVar,...) > character() stringvar >in my fortran code. It still does not work. >The whole program is working fine because if I do not send a string through, >i.e., if I make stringvar to be a double and I just work with stringvar as a >real8 then the program works 100%. >But, the program would be a bit more efficient if I could send a string >through. >How?. >If anyone can help, please let me know. >Thanks >Antonie Kotze
Wed, 18 Jun 1902 08:00:00 GMT

Roger Caffi #5 / 7	Calling Fortran 77 dll's from Visual Basic under Excel Quote: > I am using Absoft Fortran 77 to create DLL's and I then call them from > VBA under Excel97. I have been doing this for quite some time now. > I have no trouble in sending variables of doubles and integers OR arrays of > integers or doubles through to the DLL's. > STRINGS, however, seems to be a problem. I have never send a string through to > a DLL and this now stumbles me. Basically, character strings are non-standard and are implemented totally differently on every system and every language under the sky. Well, that may be a slight exaggeration, but it will do. Add to that the attempts by some misguided vendors (MS?) to introduce Unicode, where the character string isn't even in ASCII any more, and it becomes a farce. What you can do fairly reliably however is to explicitely convert the string to a byte vector, character by character and in VB, and then pass that in the usual manner to the DLL. This does work. It bypasses the whole character string farce. This is useful when you call a CommonDialogBox in VB and then pass the returned filename to the DLL for instance. But check in the program that there is something in the string: if the user "cancels" out of the box nothing is returned. I think the latest VB does have some extra features for handling character strings to overcome some of these problems (or was it DVF v6?), but why bother? The compute time to do the conversion to bytes is essentially zero. Cheers, Roger -- Roger Caffin (Dr) Director Berrilee Consulting Services P/L 5 Charltons Ck Rd Berrilee NSW 2159 Australia All the usual disclaimers apply....
Wed, 18 Jun 1902 08:00:00 GMT

Ron Sverdlove x25 #6 / 7	Calling Fortran 77 dll's from Visual Basic under Excel Quote: >I don't know much about Fortran 77 but I seem to remember from my Fortran 90 >days strings need to be passed null terminated >this can be acheived in VB by somthing like the following: > Dim StringVar as String >'''''''''''''''''''''''''''''''''''''''''''' > 'Before the API call > StringVar = StringVar & Chr(0) >'''''''''''''''''''''''''''''''''''''''''''''' >Call test(....., StringVar,...) >I haven't tested this but I hope it works for you. >Matt From the above, it appears that you never had any "Fortran 90 days". -- Ronald Sverdlove Computing Systems Research Tel. 609-734-2517 CN 5300 FAX 609-734-2662 Princeton, NJ 08543-5300
Wed, 18 Jun 1902 08:00:00 GMT

Marco A. Garci #7 / 7	Calling Fortran 77 dll's from Visual Basic under Excel Oops! I just realized that the heading said f77 and not f90. So the Fortran portion should be declared as follows: stdcall subroutine MyStringSub(MyString) character255 MyString Marco Garcia Canaima Software Quote: >When passing strings from VB to Fortran, you need to keep in mind that VB >stores strings as BStrings. This format is basically not compatible with the >one used by Fortran. BStrings are wide strings (i.e. each character takes 2 >bytes), they are null terminated (actually double-null terminated), and have >the length of the string right in front. A pointer to a bstring points to >the first character of the string. As a rule, BStrings should only be >modified through the supplied OLE-API, so you are not supposed to change a >Bstring from inside Fortran (unless you do it calling the appropriate >OLE-API). Now, the trick to pass BStrings from VB to Fortran is to do it by >value. In the VB end, you declare the Fortran sub as: >MyText As String) >on the Fortran end, you declare the subroutine as >stdcall subroutine MyStringSub(StringPtr) >character(len=255) MyString >pointer (StringPtr, MyString) >: >: >You must make sure that MyString is long enough for the strings you are >passing. Also, MyString will be null terminated, so you have to scan the >string to find its length. This trick works because VB will convert the >passed Bstring into a Multibyte string when calling API functions by Value. >So what you get in your Fortran side is basically a pointer to a normal >C-style string. >For those of you that have been struggling with this problem, you should >visit our web pages in about two more weeks. We will publish a library of >subroutines (actually, a portion of our f90ADO library) that will allow >passing bstrings back and forth between Fortran and VB. >Marco A. Garcia >Canaima Software >3981 Utah St. >San Diego, CA 92104 >U.S.A. >http://www.canaimasoft.com >Developers of f90SQL and f90ADO, >the Complete Database Connectivity Solution for Fortran >>Hi all >>I am using Absoft Fortran 77 to create DLL's and I then call them from >>VBA under Excel97. I have been doing this for quite some time now. >>I have no trouble in sending variables of doubles and integers OR arrays of >>integers or doubles through to the DLL's. >>STRINGS, however, seems to be a problem. I have never send a string through >to >>a DLL and this now stumbles me. >>I tried various ways. I declare the string in VBA as for instance >>Byval StringVar as String >>I then dimension the string to be a fixed length like >>Dim StringVar as String8 >>or >>Static StringVar as String8 >>On the Fortran side I then have >> STDCALL subroutine test(....., StringVar,...) >> character8 stringvar >>This does not work. What is wrong?? >>I also tried to have >> STDCALL subroutine test(....., StringVar,...) >> character() stringvar >>in my fortran code. It still does not work. >>The whole program is working fine because if I do not send a string >through, >>i.e., if I make stringvar to be a double and I just work with stringvar as >a >>real*8 then the program works 100%. >>But, the program would be a bit more efficient if I could send a string >>through. >>How?. >>If anyone can help, please let me know. >>Thanks >>Antonie Kotze
Wed, 18 Jun 1902 08:00:00 GMT

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