pascal 中的同时变量赋值

发布于 2024-09-07 08:56:49 字数 534 浏览 4 评论 0原文

我希望在 Pascal 中同时进行变量赋值。

据我所知，这是不可能的。谷歌搜索这个问题，我可以看到许多编程语言都实现了这一点，但我找不到如何在 Pascal 中做到这一点。

例如，在Python中我可以这样做：

(x, y) = (y, x)

在Pascal中，我需要一个额外的变量来保存x被删除之前的值，如下所示：

bubble := x;
x := y;
y := bubble;

那么，Pascal中是否有同时赋值，或者我应该将代码重写为类似的内容上面那个泡泡？

我不仅需要进行交换；还需要进行交换。有时我必须做这样的事情：

(x,y) = (x+1,y+x)

像下面这样做可以吗？

old_x := x;
old_y := y;
x := x + 1; // maybe x := old_x + 1;
y := old_y + old_x;

原文

I wish to do simultaneous variable assignment in Pascal.

As far as I know, it's not possible. Googling on the issue, I can see that many programming languages implement that, but I can't find how to do it in Pascal.

For example, in Python I can do this:

(x, y) = (y, x)

In Pascal, I need an additional variable to hold the value of x before it's removed, something like this:

bubble := x;
x := y;
y := bubble;

So, is there simultaneous assignment in Pascal, or should I rewrite the code to something like the bubble thing above?

I don't just have to do swaps; sometimes I have to do things like this:

(x,y) = (x+1,y+x)

Would it be ok to do it like the following?

old_x := x;
old_y := y;
x := x + 1; // maybe x := old_x + 1;
y := old_y + old_x;

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那些过往 2024-09-14 08:56:53

我对 Pascal 一点也不熟悉，但我找不到任何特殊的 swap 函数可以满足您的要求。

无论如何，你所做的都是完全合理的； swap 的任何标准实现都需要一个临时变量来保存要交换的值之一。我在上面编写的代码中唯一要更改的是将变量重命名为 temp，以明确该变量仅出于交换目的而临时存在：

temp := x;
x := y;
y := temp;

编辑： 更改 x 和 y 时所做的操作也没有任何问题。如果您需要保留旧值作为计算的一部分，那么将旧值分配给变量然后使用它是完全可以的。

I'm not familiar at all with Pascal, but I can't find any special swap function that does what you want.

In any case, what you're doing is perfectly reasonable; any standard implementation of swap requires a temporary variable to hold one of the values being swapped. The only thing I would change in the code you have written above is to rename the variable to temp, to make it clear that the variable only exists temporarily for the purposes of the swap:

temp := x;
x := y;
y := temp;

EDIT: There's also nothing wrong with what you're doing when changing x and y. If you need to keep the old value as part of your calculations, it's perfectly fine to assign the old value to a variable and then use it.

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