Fix examples/json_lines.cpp

[mrgharabaghi]

The extra newline throws an exception.

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[nlohmann]

What is your exact error message? The code of docs/examples/json_lines.cpp compiles fine as-is.

[gregmarr]

The original report says it throws an exception, so I assume this is a runtime error, and the error is on the json::parse of an empty line after the last valid line.

[mrgharabaghi]

As gregmarr said, this is a runtime error. Sorry, there is no problem with this example. As you can see on the below snippet, I put 4 extra whitespaces before )"; on 6th line. I think this exception is related to the <nlohmann/json.hpp>'s core. Should I have to open a Bug Report issue?

int main() {
    input << R"({"name": "Gilbert", "wins": [["straight", "7♣"], ["one pair", "10♥"]]}
             {"name": "Alexa", "wins": [["two pair", "4♠"], ["two pair", "9♠"]]}
             {"name": "May", "wins": []}
             {"name": "Deloise", "wins": [["three of a kind", "5♣"]]} 
    )";

    try
    {
        while (std::getline(input, line))
        {
            std::cout << json::parse(line) << std::endl;
        }
    }
    catch (json::parse_error& ex)
    {
        std::cerr << "parse error at byte " << ex.byte << std::endl;
    }
}

{"name":"Gilbert","wins":[["straight","7ΓÖú"],["one pair","10ΓÖÑ"]]}
{"name":"Alexa","wins":[["two pair","4ΓÖá"],["two pair","9ΓÖá"]]}
{"name":"May","wins":[]}
{"name":"Deloise","wins":[["three of a kind","5ΓÖú"]]}
parse error at byte 5

[nlohmann]

Sorry: I meant I can compile and run the example as-is.

[gregmarr]

Sorry: I meant I can compile and run the example as-is.

I can confirm the error with the blank line at the end: https://www.godbolt.org/z/3hzGz75WE

And now it's gone. It was there a minute ago with the single newline at the end, but now it's not, it must have still been updating. It's only there with two or more newlines at the end.

[gregmarr]

As you can see on the below snippet, I put 4 extra whitespaces before )"; on 6th line.

Yeah, that's the source of the issue. You changed from having a newline at the end of the data, which is handled cleanly, to having whitespace after the final newline, which does not get handled cleanly. You'd need to strip leading whitespace from line before passing it to json::parse() if you wanted to support that.

[nlohmann]

Anything to do here then? And: if so, please create an PR for the develop branch and not the gh-pages.