小谈话异常--为什么变量总是一样的，但是计算布尔值时它们是不同的？

Question

我选择尝试适用于AOC 2022益智4的Smalltalk。如果满足约束，我将对每一行进行预测并增加计数器。我想弄明白为什么'2-8,3-7‘线不符合要求。因此，我开始打印值来检查正在发生的事情。显然，当通过向对象发送displayNl消息输出值时，firstMax、firstMin等值通过循环总是相同的，其中包含来自‘2-4、6-8’的信息，即第一行。但是，更奇怪的是，即使第一行不满足约束，计数器也会增加一次。然后，我发现在检查'6-6,4-6‘行时，它实际上计算了布尔值overlapFirst和overlapSecond值，因此ifTrue会增加计数器！为什么！？

编辑:我解决了这个问题，把它放在这里，而不是首先将子字符串放入一个变量中：

firstAssignment := (line substrings: ',') first. 
secondAssignment := (line substrings: ',') last. 

这是否意味着您不能重新分配OrderedCollection？

通过运行命令：gst main.st，我正在用gnu小对话来运行这个程序。

这是data.txt。

2-4,6-8
2-3,4-5
5-7,7-9
2-8,3-7
6-6,4-6
2-6,4-8

这是main.st。

file := FileStream open: 'data.txt' mode: FileStream read.
count := 0.
file linesDo: [ 
  :line | 
  assignments := line substrings: ','.
  firstAssignment := assignments first.
  secondAssignment := assignments last.
  first := firstAssignment substrings: '-'.
  second := secondAssignment substrings: '-'.
  firstMin := first first.
  firstMax := first last.
  secondMin := second first.
  secondMax := second last.
  overlapFirst := (firstMin <= secondMin) & (firstMax >= secondMax).
  overlapSecond := (secondMin <= firstMin) & (secondMax >= firstMax).

  overlap := overlapSecond | overlapFirst.

  line displayNl.
  overlapFirst displayNl.
  overlapSecond displayNl.
  firstMin displayNl.
  firstMax displayNl.
  secondMin displayNl.
  secondMax displayNl.

  overlap ifTrue: [
  'Incremented!' displayNl.
  count := count + 1.
  ].
].

Transcript show: count asString.


file close.

Answer 1

这解决了我的问题..。我还编辑了这篇文章，我需要学习如何在堆栈溢出中做一些事情。

我换了第5行和第6行。

file := FileStream open: 'data.txt' mode: FileStream read.
count := 0.
file linesDo: [ 
  :line | 
  firstAssignment := (line substrings: ',') first. 
  secondAssignment := (line substrings: ',') last.
  first := firstAssignment substrings: '-'.
  second := secondAssignment substrings: '-'.
  firstMin := first first asInteger.
  firstMax := first last asInteger.
  secondMin := second first asInteger.
  secondMax := second last asInteger.
  overlapFirst := (firstMin <= secondMin) & (firstMax >= secondMax).
  overlapSecond := (secondMin <= firstMin) & (secondMax >= firstMax).

  overlap := overlapSecond | overlapFirst.

  line displayNl.

  overlap ifTrue: [
  'Incremented!' displayNl.
  count := count + 1.
  ].
].

Transcript show: count asString.


file close.