Please Help on some basics on prolog

Question

I want to write a program that deletes any occurrence of a member in a given list, as bellow:

deleteall(1,[1,2,3,1,3,2,5],Out)                
Out= [2,3,3,2,5]

How can I do that? This is my attempt:

deleteall(X,[],[]).                
deleteall(X,[H1|T1],[H2|T2]) :- deleteall (X,T1,T2).

Welcome to Stack Overflow! We want to help, but we like to see you make an attempt first. What have you tried, and where are you stuck? — Michael Petrotta, Apr 21 '12 at 01:27
See [this answer](http://stackoverflow.com/questions/6441527/simple-prolog-delete-from-list/6441803#6441803) — false, May 29 '12 at 08:58

Chetter Hummin · Accepted Answer · 2012-04-21T02:00:23.043

0

Please try the following. You were missing a condition in your original program.

deleteall(_,[],[]).
deleteall(X,[X|T1],T2) :- deleteall(X,T1,T2).
deleteall(X,[H1|T1],[H1|T2]) :- not(X=H1), deleteall(X,T1,T2).

edited Apr 21 '12 at 02:00

answered Apr 21 '12 at 01:46

Chetter Hummin

Thank you for your reply, but it doesn't work for me. I am using win prolog 4.7 . – Mahdi Apr 21 '12 at 01:50
Well, I'm using XSB-Prolog. What error are you getting? – Chetter Hummin Apr 21 '12 at 01:51
It doesn't back any error, just say no – Mahdi Apr 21 '12 at 01:52
Try invoking with deleteall(1,[1,2,3,1,3,2,5],O). – Chetter Hummin Apr 21 '12 at 01:53
out is a constant, not a variable – Chetter Hummin Apr 21 '12 at 01:53

1 Answers1