Something like istream::getline() but with alternative delim characters?

Question

What's the cleanest way of getting the effect of istream::getline(string, 256, '\n' OR ';')?

I know it's quite straightforward to write a loop, but I feel that I might be missing something. Am I?

What I used:

while ((is.peek() != '\n') && (is.peek() != ';'))
    stringstream.put(is.get());

score 3 · Answer 1 · edited May 23 '17 at 10:29

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There's std::getline. For more complex scenarios one might try splitting istream_iterator or istreambuf_iterator with boost split or regex_iterator (here is an example of using stream iterators).

edited May 23 '17 at 10:29

Community

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answered Oct 15 '12 at 07:23

ArtemGr

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`std::getline` is good because it has an overload for `std::string` which makes string I/O much, much easier (at least in my opinion). – dreamlax Oct 15 '12 at 07:25
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`std::getline` doesn't help in this case when the OP want multiple line endings/separators. – Some programmer dude Oct 15 '12 at 07:42

score 3 · Accepted Answer · answered Oct 15 '12 at 07:47

3

Unfortunately there is no way to have multiple "line endings". What you can do is read the line with e.g. std::getline and put it in an std::istringstream and use std::getline (with the ';' separator) in a loop on the istringstream.

Although you could check the Boost iostreams library to see it it has functionality for it.

answered Oct 15 '12 at 07:47

Some programmer dude

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Ok, thanks, that's quite nice! I wrote a loop that std::stringstream.put():ed every char until it found '\n' or ';', and then used stringstream.str() to get the string. – Erika Oct 15 '12 at 08:02

WhiZTiM · Answer 3 · 2016-08-26T21:43:04.450

Here is a working implementation:

enum class cascade { yes, no };
std::istream& getline(std::istream& stream, std::string& line, const std::string& delim, cascade c = cascade::yes){
    line.clear();
    std::string::value_type ch;
    bool stream_altered = false;
    while(stream.get(ch) && (stream_altered = true)){
        if(delim.find(ch) == std::string::npos)
            line += ch;
        else if(c == cascade::yes && line.empty())
            continue;
        else break;
    }
    if(stream.eof() && stream_altered) stream.clear(std::ios_base::eofbit);
    return stream;
}

The cascade::yes option collapses consecutive delimiters found. With cascade::no, it will return an empty string for each a second consecutive delimeter found.

Usage:

const std::string punctuation = ",.';:?";
std::string words;
while(getline(istream_object, words, punctuation))
    std::cout << word << std::endl;

See its usage Live on Coliru

A more generic version will be this

Something like istream::getline() but with alternative delim characters?

3 Answers3