Fortran Programming Guide

Argument-Passing by Reference or Value

In general, Fortran routines pass arguments by reference. In a call, if you enclose an argument with the f77 and f90 nonstandard function %VAL(), the calling routine passes it by value.

In general, C passes arguments by value. If you precede an argument by the ampersand operator (&), C passes the argument by reference using a pointer. C always passes arrays and character strings by reference.