Re: A question about list
"Gregory Bourassa" <[email protected]>
| Newsgroups | gmane.comp.gnu.prolog.general |
|---|---|
| Message-ID | <[email protected]> |
Yang, First the notion of "assign its value" is not very natural in Prolog. Be aware, if the variable is already "bound" to a value, you CANNOT assign a new value to it in standard Prolog. If Var is previously unbound, your answer is incredibly simple: List = [Var | _] Prolog's pattern matching ensures that Var is bound to the value of the first element in List. Regards. Gregory Bourassa On Oct 23, "=?gb2312?B?1dTR9A==?=" <[email protected]> wrote: Hi, all: I am a beginner in GNU prolog and now encounter a problem. Given a list that has been instantiated, I want to get its first element and assign its value to a variable. How can I do it? I have tried nth(1, List, Var), but it does not help. Could any body tell me? Zhao,Yang 2006-10-24 _______________________________________________ Users-prolog mailing list [email protected] <a href='http://lists.gnu.org/mailman/listinfo/users-prolog'>http://lists.gnu.org/mailman/listinfo/users-prolog</a>