1. ENERGY 211 / CME 211
Lecture 29
December 3, 2008

2. Command-line Arguments
main actually accepts arguments:
int argc: number of command-line arguments
char *argv[]: array of argc C strings containing the arguments
First argument, argv[0], is name of the executable
Arguments separated by spaces
Typically, arguments used to customize execution

3. Calling FORTRAN from C++
Add _ to name of FORTRAN function
Pass addresses of non-array arguments
Remember that matrices are stored in column order in FORTRAN, so be sure to keep code consistent
FORTRAN functions must be declared like other external functions
Precede declaration with extern "C" so simple C naming convention used

4. Linking FORTRAN with C++
Use gfortran –c to compile each FORTRAN source file
On elaine or other workstations, can also use f90, but that is not a GNU compiler and doesn't always work with C++ code compiled with g++
Use g++ -c to compile each C++ source file
Use g++ to link all .o files

5. Calling C++ from FORTRAN
Functions called by FORTRAN code must accept pointers to non-array arguments, because FORTRAN passes by reference
In C++ code (as opposed to C), precede function declarations with extern "C"
End function names with _
Remember matrix storage conventions!

6. On the FORTRAN side
Leave out _ at end of C/C++ function names, FORTRAN compiler adds them automatically
Declare functions as external, like other external FORTRAN routines
Pass arguments normally (ignore that they are pointers on the C/C++ side)
A double in C++ corresponds to type double precision in FORTRAN

7. Linking C++ with FORTRAN
Use gfortran –c to compile each FORTRAN source file
Use g++ -c to compile each C++ source file
Use gfortran to link all .o files
If C++ code uses any Standard Library code, must explicitly link with it
Library name is libstdc++.so

8. Next Time Mop-up! Final project discussion
Loading dynamic libraries in UNIX
private and friend classes
More overloading