— Function: int astr_cat (Autostr *dest, const Autostr *src)
Concatenates a copy of the contents of src onto the end of the
contents of dest. Returns 0 if the function succeeded, or
-1 if there was insufficient memory.
— Function: int astr_cat_s (Autostr *astr, const char *chars)
Concatenates a copy of the characters referenced by chars onto the
end of the contents of astr. Returns 0 if the function succeeded,
or -1 if there was insufficient memory.
— Function: int astr_cat_c (Autostr *astr, int c)
Concatenates c (converted to a ‘char’) onto the end of the
contents of astr. c may not be zero. Returns 0 if the
function succeeded, or -1 if there was insufficient memory.