doc

Author: scivision

test/pointer/README.md

@@ -6,7 +6,10 @@ and modern "nullptr" in
 [C23](https://en.cppreference.com/w/c/language/nullptr)
 are represented in Fortran
 [iso_c_binding](https://fortranwiki.org/fortran/show/iso_c_binding).
+
 Unlike in C / C++, do not check equality with C_NULL_PTR in Fortran.
 Instead, by definition the
 [c_associated()](https://fortranwiki.org/fortran/show/c_associated)
 logical function returns ".false." if the C_PTR is C_NULL_PTR, and ".true." otherwise.
+See [strptime.f90](./strptime.f90)
+for an example of checking in Fortran for a C null pointer returned from a function.