https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972152#M24220 I have a library of mixed C and FORTRAN routines. Some of the FORTRAN routines have optional arguments. How can I call one of thse routines from a C routine? I have no trouble calling a FORTRAN routine from a C routine when I do not use optional arguments. With optional arguments I get a access violation when I use an optional argument. Thu, 01 Nov 2001 05:48:57 GMT multivac 2001-11-01T05:48:57Z https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972152#M24220 I have a library of mixed C and FORTRAN routines. Some of the FORTRAN routines have optional arguments. How can I call one of thse routines from a C routine? I have no trouble calling a FORTRAN routine from a C routine when I do not use optional arguments. With optional arguments I get a access violation when I use an optional argument. Thu, 01 Nov 2001 05:48:57 GMT https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972152#M24220 multivac 2001-11-01T05:48:57Z https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972153#M24221 You must pass NULL (zero by value) for the omitted arguments.<BR /><BR />Steve Thu, 01 Nov 2001 09:04:53 GMT https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972153#M24221 Steven_L_Intel1 2001-11-01T09:04:53Z https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972154#M24222 That will not work for me. I have a 'C' main program. The FORTRAN routine with the optional arguements is called by the 'C' mail program. Even when the optional argument is included with a real argument or a NULL, I get an access violation. I believe I have a compiler switch/ prototype definition problem. I could send you the program and project file to look at ... Fri, 02 Nov 2001 03:40:04 GMT https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972154#M24222 multivac 2001-11-02T03:40:04Z https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972155#M24223 Do you declare the argument as having the OPTIONAL attribute and do you use PRESENT to test for it? Passing NULL should work then. If you need more help, send details to vf-support@compaq.com<BR /><BR />Steve Fri, 02 Nov 2001 04:07:57 GMT https://community.intel.com/t5/Software-Archive/Mixed-Language-Programming-and-Optional-Arguments/m-p/972155#M24223 Steven_L_Intel1 2001-11-02T04:07:57Z