scanf函数IStream对象上 [英] scanf on an istream object

问题描述

请注意：我见过的帖子<一个href=\"http://stackoverflow.com/questions/14330637/what-is-the-cin-analougus-of-scanf-formatted-input\">What是scanf的格式化输入的CIN analougus？提出的问题和后在这里不解决我的问题了。该职位旨在为C ++ - 的方式来做到这一点，但正如我前面提到的，不方便只使用C ++ - 的方式有时做到这一点，我有这明显的例子

NOTE: I've seen the post What is the cin analougus of scanf formatted input? before asking the question and the post doesn't solve my problem here. The post seeks for C++-way to do it, but as I mentioned already, it is inconvenient to just use C++-way to do it sometimes and I have clear examples for that.

我想从IStream对象读取数据，有时候不方便只使用C ++ - 风格方面，如运营商>>，例如该数据是特殊形式123：456所以你要灌输，使'：'：要读作串并转换，或00123为空（在scanf中的％D，它是非常哈克，而非％D）小数代替八进制（相对于在scanf的％D），以及可能的其他许多情况

I am trying to read data from an istream object, and sometimes it is inconvenient to just use C++-style ways such as operator>>, e.g. the data are in special form 123:456 so you have to imbue to make ':' as space (which is very hacky, as opposed to %d:%d in scanf), or 00123 where you want to read as string and convert decimal instead of octal (as opposed to %d in scanf), and possibly many other cases.

我选择istream的作为接口的原因是因为它可以产生的，因此更加灵活。例如，我们可以创建内存流，或者实时生成一些定制流等C语言风格的FILE *，在另一方面，是非常有限的，至少在一个符合标准的方式，在创建自定义的流。

The reason I chose istream as interface is because it can be derived and therefore more flexible. For example, we can create in-memory streams, or some customized streams that generated on the fly, etc. C-style FILE*, on the other hand, is very limited, at least in a standard-compliant way, on creating customized streams.

所以我的问题是，有没有办法做到IStream对象上类似scanf数据提取？我想的fscanf读取内部逐个字符使用龟etc FILE *，同时也的IStream提供这样的接口。因此，它是直接复制粘贴的fscanf的code和替换文件*与istream对象可能的，但是这是非常哈克。是否有一个更聪明和更清洁的方式，或者是有一些现有的工作对这个？

So my questions is, is there a way to do scanf-like data extraction on istream object? I think fscanf internally read character by character from FILE* using fgetc, while istream also provides such interface. So it is possible by just copying and pasting the code of fscanf and replace the FILE* with the istream object, but that's very hacky. Is there a smarter and cleaner way, or is there some existing work on this?

感谢。

推荐答案

根据@ tmyklebu的评论，我实现了streamScanf它通过fopencookie的包装istream的为FILE *：的 https://github.com/likan999/$c$cjam/blob/master/Common/StreamScanf.cpp

Based on @tmyklebu's comment, I implemented streamScanf which wraps istream as FILE* via fopencookie: https://github.com/likan999/codejam/blob/master/Common/StreamScanf.cpp

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