```{index} single: variable (Peta::FFI) ``` ```{index} single: Peta::FFI::variable ``` # variable A library's global variable as a Perl scalar. ## Synopsis ```perl my $optind = Peta::FFI::variable($libc, "optind", "i"); print $$optind, "\n"; # reads the C variable $$optind = 1; # writes it ``` A reference to a scalar bound to the variable: reading `$$var` reads the C variable at that moment, assigning to it writes the variable, for any type `store` can write; a `p` variable is read-only. The library stays loaded while the scalar lives. Croaks when the library has no such symbol.