Re: ctypes: error passing a list of str to a fortran dll
On 5 jun, 06:15, Charles Sanders [EMAIL PROTECTED] wrote: luis wrote: I'm using ctypes to call afortrandllfrom python. I have no problems passing integer and double arryas, but I have an error with str arrys. For example: [snip] I do not know about MicrosoftFortrancompilers (your mention ofdllindicates you are probably using MS), nor much about Python, but the C equivalent of a givenFortrancall is operating system and compiler dependent. You should consult theFortran compiler manual for the compiler used to create theDLL. Despite this, many (but not all) C toFortraninterfaces have the following characteristics + C name isFortranname in lower case +FortranREAL, DOUBLE PRECISION, INTEGER etc parameters are pointers to the parameter in C, ie float*, etc +FortranREAL etc arrays are pointers in C (same as C arrays decay to pointers). +FortranCHARACTER and CHARACTER arrays are passed as TWO parameters, one a pointer to the start of the variable or array, and the other the length as an integer, not a pointer. The length parameters follow all other parameters, in order of the character variables/arrays. Variations I have seen (all on Unix) include using upper case instead of lower, prepending (or postpending) an underscore (or other character(s)) to the subroutine or function name, and using special character descriptors (packing address and length into one word) for character variables. There are almost certainly more variations that I have not seen. For example, given aFORTRANdeclaration SUBROUTINE X( CV, RV, CA, N ) CHARACTER*(*) CV REAL RV CHARACTER*(*) CA(*) INTEGER N The C equivalent is likely to be void x( char *pcv, float *prv, char *pca, int *pn, int lv, int la) Where lv will hold the length of cv and la the length of each element of ca (required to be the same for all elements of the array).Fortranuses fixed length character strings, padded with blanks. Given the error message ValueError: Procedure probably called with not enough arguments (4 bytes missing) I suspect that yourFortrancompiler is one of the many which do this, and the missing 4 bytes are the integer length of each element of the character array. Also, I noticed you seem to be passing an array of character pointers rather than an array of characters. It is doubtful thatFortrancan handle this. You will probably have to pad the strings to a maximal length with spaces, concatanate then into one big string, and pass this by reference together with their padded length. YourFortranmay (but probably won't) have extensions that allow you to pass an array of character pointers. Charles The solution proposed by Jugoslav Dujic, from comp lang fortran is #Python script calling fortran subroutine from ctypes import * ap = windll.LoadLibrary(self.locationDll) ap.TEST_02.restype=None myCadena='D:\BBDD\PythonScripts\pru.txt' strLen=len(myCadena) pf_myCadena = c_char_p(myCadena) pf_srLen = c_int(strLen) ap.TEST_02(pf_myCadena,pf_srLen) !fortran dll subroutine TEST_02(s) !DEC$ ATTRIBUTES DLLEXPORT :: TEST_02 !DEC$ATTRIBUTES REFERENCE:: s !INTEGER(4):: n CHARACTER(*):: s open (unit=31,file=trim(s)) write(31,'(f0.1)') 1.0 write(31,*) trim(s) write(31,'(i0)') len_trim(s) close(31) return END subroutine Regards -- http://mail.python.org/mailman/listinfo/python-list
ctypes: error passing a list of str to a fortran dll
I'm using ctypes to call a fortran dll from python. I have no problems passing integer and double arryas, but I have an error with str arrys. For example: StringVector = c_char_p * len(id) # id is a list of strings Id_dat=StringVector() for i in range(len(Id)): ...Id_dat[i]=id[i] n=c_int(len(Id_dat)) myDll = windll.LoadLibrary(org) myDll.myFunc(byref(n), byref(Id_dat)) and then ValueError: Procedure probably called with not enough arguments (4 bytes missing) In a similar way I have bo problemns with int or double arryas Some suggestions are wellcome ! -- http://mail.python.org/mailman/listinfo/python-list
Re: ctypes: error passing a list of str to a fortran dll
luis wrote: I'm using ctypes to call a fortran dll from python. I have no problems passing integer and double arryas, but I have an error with str arrys. For example: [snip] I do not know about Microsoft Fortran compilers (your mention of dll indicates you are probably using MS), nor much about Python, but the C equivalent of a given Fortran call is operating system and compiler dependent. You should consult the Fortran compiler manual for the compiler used to create the DLL. Despite this, many (but not all) C to Fortran interfaces have the following characteristics + C name is Fortran name in lower case + Fortran REAL, DOUBLE PRECISION, INTEGER etc parameters are pointers to the parameter in C, ie float*, etc + Fortran REAL etc arrays are pointers in C (same as C arrays decay to pointers). + Fortran CHARACTER and CHARACTER arrays are passed as TWO parameters, one a pointer to the start of the variable or array, and the other the length as an integer, not a pointer. The length parameters follow all other parameters, in order of the character variables/arrays. Variations I have seen (all on Unix) include using upper case instead of lower, prepending (or postpending) an underscore (or other character(s)) to the subroutine or function name, and using special character descriptors (packing address and length into one word) for character variables. There are almost certainly more variations that I have not seen. For example, given a FORTRAN declaration SUBROUTINE X( CV, RV, CA, N ) CHARACTER*(*) CV REAL RV CHARACTER*(*) CA(*) INTEGER N The C equivalent is likely to be void x( char *pcv, float *prv, char *pca, int *pn, int lv, int la) Where lv will hold the length of cv and la the length of each element of ca (required to be the same for all elements of the array). Fortran uses fixed length character strings, padded with blanks. Given the error message ValueError: Procedure probably called with not enough arguments (4 bytes missing) I suspect that your Fortran compiler is one of the many which do this, and the missing 4 bytes are the integer length of each element of the character array. Also, I noticed you seem to be passing an array of character pointers rather than an array of characters. It is doubtful that Fortran can handle this. You will probably have to pad the strings to a maximal length with spaces, concatanate then into one big string, and pass this by reference together with their padded length. Your Fortran may (but probably won't) have extensions that allow you to pass an array of character pointers. Charles -- http://mail.python.org/mailman/listinfo/python-list
