比较 Forth 中的字符串

Question

我从键盘输入字符串并进行比较。但它永远不会返回 0，即使字符串相等。

CREATE word1 14 ALLOT
: .getword1 word1 14 BLANK word1 14 EXPECT ;
CREATE word2 14 ALLOT
: .getword2 word2 14 BLANK word2 14 EXPECT ;
: input_words
." " CR
." First word:" CR
.getword1
." " CR
." Second word:" CR
.getword2
word2
word1
word1 word2 compare
." " CR
.s
;

它永远不会为我的字符串返回 0：

First word:
e
Second word:
e
<1> 1

定义有问题吗？

Answer 1

compare具有以下堆栈签名(cstr1 count1 cstr2 count2 -- n (。它需要字符串的地址及其计数(长度(

create word1 ," Test"  Store counted string in word1
create word2 ," Test"  Store counted string in word2
word1 count type Test ok
word2 count type Test ok
word1 . word2 .  4992752 4992848  ok   addresses of word1 and word2
word1 count word2 count .s compare
DATA STACK
top
4 0000:0004     count2
4992849 004C:2F51     address word2 + 1
4 0000:0004     count1
4992753 004C:2EF1     address word1 + 1
ok-1
. 0  ok

进一步比较

char S word1 1+ c!  ok   Change the T in word1 to an S
word1 count type Sest ok
word1 count word2 count compare . -1  ok
char R word2 1+ c!  ok   Change the T in word1 to an R
word2 count type Rest ok
word1 count word2 count compare . 1  ok

我的系统上没有 EXPECT 词来测试您的代码，但我怀疑您的getwordx词在堆栈上留下了各种项目，这意味着比较不会导致异常，但不会进行您期望的比较。

编辑：已实现EXPECT的答案。

 Creating ANS forth EXPECT. I have ACCEPT not EXPECT in my Forth
CELL USER SPAN
: EXPECT   addr ct -- 
ACCEPT SPAN ! ;
 Answer to question
: getword   addr ct -- 
2DUP BL FILL     Fill addr for count with blanks
EXPECT ;         Refill addr with characters typed at the prompt.
CREATE word1 14 ALLOT
CREATE word2 14 ALLOT
: wtype    addr -- ;
14 -TRAILING TYPE ;
: input_words   ;
CR ." First  Word : " word1 14 getword
CR ." Second Word : " word2 14 getword
CR word1 wtype 5 SPACES word2 wtype
CR word1 14 word2 14 compare .
;

由于两个缓冲区都填充了任何未使用字符的空白，因此比较仍然有效。

input_words 
First  Word : Test 
Second Word : Test 
Test     Test
0  ok
input_words 
First  Word : Rest 
Second Word : Test 
Rest     Test
-1  ok