Prolog 程序范例

3的阶乘：

predicates

factorial(unsigned,real)

clauses

factorial(1,1):-!.

factorial(X,FactX):-

Y=X-1,

factorial(Y,FactY),

FactX = X*FactY.

goal

X=3,

factorial(X,Y).

输出表

domains

list = integer*

predicates

write_a_list(list)

clauses

write_a_list([]).

write_a_list([H|T]):-

write(H),nl,

write_a_list(T).

goal

write_a_list([1,2,3]).

统计表元素个数

domains

list = integer*

predicates

length_of(list,integer)

clauses

length_of([], 0).

length_of([_|T],L):-

length_of(T,TailLength),

L = TailLength + 1.

goal

length_of([1,2,3],L).

每个元素加1

domains

list = integer*

predicates

add1(list,list)

clauses

add1([], []).

add1([Head|Tail],[Head1|Tail1]):- Head1= Head+1,

add1(Tail,Tail1).

goal

add1([1,2,3,4],NewList).

删除整数表中的负数

domains

list = integer*

predicates

discard_negatives(list,list)

clauses

discard_negatives([],[]).

discard_negatives([H|T],ProcessedTail):-

H < 0,!,

discard_negatives(T, ProcessedTail). discard_negatives([H|T],[H|ProcessedTail]):- discard_negatives(T, ProcessedTail).

goal discard_negatives([2,-45,3,468],X).

判断表成员

domains

namelist = name*

name = symbol

predicates

member(name,namelist)

clauses

member(Name,[Name|_]).

member(Name,[_|Tail]):-

member(Name,Tail).

goal

member(susan,[ian,susan,john]).

合并表

domains

integerlist = integer*

predicates

append(integerlist,integerlist,integerlist) clauses

append([],List,List).

append([H|L1],List2,[H|L3]):-

append(L1,List2,L3).

goal

append([1,2,3],[5,6],L).

输出表中元素

domains

integerlist = integer*

namelist = symbol*

predicates

writelist(integerlist)

writelist(namelist)

clauses

writelist([]).

writelist([H|T]):-

write(H, " "),

writelist(T).

goal writelist([1,2,3,4]),nl.

找出一个数字链表的最大数值。

domains/*领域段*/

list=integer*.

predicates/*谓词段*/

max(list,integer)

clauses/*子句段，存放所有的事实和规则*/

max([H], H).

max([H | T], H) :- max(T, X), H >= X.

max([H | T], X) :- max(T, X), H < X.

动态生成关于N个学生（包括学号、姓名、出生年月日、成绩）的内部事实数据库，并计算学生成绩的平均分。

domains

num=symbol

name=symbol

birthday=date(integer,integer,integer)

score=real

list=score*

facts

stud(num,name,birthday,score)

predicates

run

add_fact(integer)

sumlist(list,real)

clauses

run:-

write("enter the N:"),nl,

readint(N),

add_fact(N),

findall(Score,stud(_,_,_,Score),Slist),

sumlist(Slist,Sum),

Ave=Sum/N,nl,

write("the average score is :",Ave).

add_fact(N):-

N>=1,!,nl,

write("the ",N," student:"),nl,

write("num:"),

readln(Num),

write("name:"),

readln(Name),

write("year:"),

readint(Year),

write("month:"),

readint(Month),

write("date:"),

readint(Date),

write("score:"),

readreal(Score),

assertz(stud(Num,Name,date(Year,Month,Date),Score)),

N1=N-1,

add_fact(N1).

add_fact(N):-N<1.

sumlist([],0).

sumlist([H|T],Sum):-

sumlist(T,S1),

Sum=H+S1.

goal

run.

实现表的插入排序，要求表中的N个元素由键盘读入domains

element=integer

list=element*

predicates

run(list)

insert_N(list,element,list)

append(list,list,list)

write_list(list)

clauses

run(List):-readint(N),

N>0,!,

insert_N(List,N,List1),

write_list(List1),nl,

run(List1).

run(_).

insert_N([],N,[N]):-!.

insert_N([H|T],N,[H1|T1]):-H<=N,!,

H1=H,

insert_N(T,N,T1). insert_N([H|T],N,[H1|T1]):-H>N,

H1=N,

append([H],T,T1).

append([],L2,L2):-!. append([H1|T1],L2,[H1|T3]):- append(T1,L2,T3). write_list([]):-!.

write_list([H|T]):-write(H," "),write_list(T).

goal

run([]).

求和

domains

list = integer*

predicates

sumlist(list,integer)

clauses

sumlist([],0).

sumlist([H|T],Sum):-

sumlist(T,S1),

Sum=H+S1.

goal

sumlist([1,2,3],Sum).

求最大值

domains

list=integer*

predicates

max(list,integer)

clauses

max([H],H).

max([H|T],H):-max(T,X),H >= X.

max([H|T],X):-max(T,X),H < X.

goal

max([1,2,4],H).

求最小值

domains

list=integer*

predicates

max(list,integer)

clauses

max([H],H).

max([H|T],H):-max(T,X),H <= X.

max([H|T],X):-max(T,X),H > X.

goal

max([1,2,4],H).

求个数

domains

list = integer*

predicates

length_of(list,integer) clauses

length_of([], 0). length_of([_|T],L):- length_of(T,TailLength), L = TailLength + 1. goal

length_of([1,2,3],L).

求平均值

predicates

adv(real,real)

clauses

adv(X,Y):-

Diff = X/Y,

write("adv= ",Diff,'\n'). goal

X=47,

Y=4,

adv(X,Y).