解析命令行参数 [英] Parsing command line arguments

问题描述

我对 prolog 很困惑，它与我曾经使用过的任何语言(多种语言)都不一样，我如何从以下位置获取 argv[0]:

I'm very confused with prolog, it's way different to any language I've ever used (many languages) How do I go about getting argv[0] from:

current_prolog_flag(argv, Argv),
write(Argv).

现在，如果我尝试输入 Argv[0] 或 Argv(0) 或 Argv<0> 它会失败.. 这让我没有任何线索，文档中的帮助也很少.. 似乎他们希望你已经成为序言专家 :D

Now if I tried to type Argv[0] or Argv(0) or Argv<0> it fails.. this leaves me with no clue and very little help from the documentation.. it seems that they expect you to already be a prolog expert :D

另一个问题，我如何将 Argv[0] 分配给一个变量，以便稍后使用write"打印它?

Another question, how would I assign Argv[0] to a variable so I can print it later using "write" ?

推荐答案

Prolog 使用匹配.

Prolog uses matching.

?- current_prolog_flag(argv, [File | Rest]).
File = 'C:\\Program Files\\pl\\bin\\swipl-win.exe',
Rest = ['--win_app'].

这匹配一个有头有尾的列表:

This matches a list with a head and the tail:

[Head | Tail]

Head 是第一个元素，Tail 是列表的其余部分.

Head is the first element and Tail is the rest of the list.

要获取最后一个元素，请使用:

To get the last element, use:

?- current_prolog_flag(argv, Argv), append(_, [Last], Argv).
Argv = ['C:\\Program Files\\pl\\bin\\swipl-win.exe', '--win_app'],
Last = '--win_app'

要获取有关 append 等函数的帮助:

To get help about functions like append:

apropos(append).

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