Question

我尝试在屏幕上打印列表元素，但是以自定义方式打印。当我编译代码时，出现这样： print

我的代码：

printTray([L0,L1,L2,L3,L4,L5,L6,L7,L8,L9,L10]) :- 
    nl,
    printLine(L0),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L1),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L2),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L3),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L4),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L5),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L6),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L7),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L8),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L9),
    print('---------+---+---+---+---+---+---+---+---+---'), nl,
    printLine(L10),
    print('---------+---+---+---+---+---+---+---+---+---'), nl.

printLine([P0,P1,P2,P3,P4,P5,P6,P7,P8,P9,P10]) :-  
    write(P0),
    print('      '),  
    write(P1),  
    print(' | '),  
    write(P2),  
    print(' | '),  
    write(P3),
    print(' | '),  
    write(P4),
    print(' | '),  
    write(P5),
    print(' | '),  
    write(P6),
    print(' | '),  
    write(P7),
    print(' | '),  
    write(P8),
    print(' | '),  
    write(P9),
    print(' | '),  
    write(P10),  
    print(' '),  
    nl.

printTray子句中的列表是托盘的行。因此，对于每一行，我逐个打印元素。我不知道这个的原因，我尝试了另一种方法但结果却是一样的。当我更改变量值的列表元素的值时会发生问题。

Answer 1

也许您只需要使用像

这样的实用程序替换所有write / 1

vwrite(V) :- var(V) -> write(' ') ; write(V).

对代码进行一些重构会导致

printTray(Tray) :- 
    nl, maplist(printLine, Tray).

printLine([P0,P1,P2,P3,P4,P5,P6,P7,P8,P9,P10]) :-  
    vwrite(P0),
    write('      '),
    maplist([P]>>(vwrite(P),write(' | ')), [P1,P2,P3,P4,P5,P6,P7,P8,P9]),
    vwrite(P10),  
    writeln(' '),
    writeln('---------+---+---+---+---+---+---+---+---+---').

vwrite(V) :- var(V) -> write(' ') ; write(V).

与此测试数据配对

tray([
    [_,_,_,_,_,_,_,_,_,_,_],
    [_,_,_,_,_,_,_,_,_,_,_],
    [y,_,_,_,_,_,_,_,_,_,_],
    [_,_,_,_,_,_,_,_,_,_,_],
    [_,_,_,_,_,_,_,_,_,_,_],
    [_,_,_,_,_,_,_,_,_,_,_],
    [_,_,_,_,_,_,_,_,1,_,_],
    [_,_,_,_,_,_,_,_,_,2,_],
    [_,_,_,_,_,_,_,_,_,_,3],
    [_,_,_,_,_,_,_,_,_,_,_],
    [_,_,_,_,_,_,_,_,_,_,_]]).

产量

?- tray(T), printTray(T).

         |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---
y        |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   | 1 |   |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   | 2 |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   |   | 3 
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---
         |   |   |   |   |   |   |   |   |   
---------+---+---+---+---+---+---+---+---+---

PROLOG中的写入不打印变量值

1 个答案: