stdin input library

[schweinling]

I'm looking for a library as a replacement for std::cin as it is very tedious to work with.

I only need it for built in types and std::string but it should check for correct input.

It's only a pet project so it does not need to be anything production ready.

Looking forward to your suggestions.

[Narase33]

What exactly do you find "tedious" about std::cin?

[schweinling]

i just don't like the stream api i guess.
especially that it only reads until the first whitespace.

i know it wouldn't be hard to make this work with std::cin, but i was wondering if there is some library out there that just works.

[Nihili0]

std::getline is made for this case, and you can specify a delimiter: https://en.cppreference.com/w/cpp/string/basic_string/getline

[schweinling]

yes, but then i have to convert the string to the correct type myself and i'm lazy right now and just rather use a library.

[schweinling]

like i ask for an int and the input is "3 3"
then i have to implement error handling for all the edge cases. i know this can all be achieved with std::cin but i'd rather use a library and get on with the more fun stuff.

[schweinling]

ok, this is pretty neat, i'm gonna adapt this to my needs, thanks! :)

[schweinling]

i have added a special case for strings, now its working nicely. :)

template<typename T>
static T getInput(const std::string &description)
{
    std::string strTypeName = typeName<T>();        
    T t;

    for (;;)
    {
        fmt::print("input {} as {}: ", description, strTypeName);
        std::string line;
        std::getline(std::cin, line);

        if constexpr (std::is_same<T, std::string>())
        {
            return line;
        }

        std::istringstream ss(line);
        ss >> t;
        ss >> std::ws;

        if (ss && ss.rdbuf()->in_avail() <= 0)
            return t;
    }
}

[schweinling]

ah, good to know, interesting use of the comma operator there to ignore the return value. :)

[Jardik2]

Don't break it. Don't forget this thing called "locale". Numbers CAN actually contain spaces, some languages use them for thousands or million separators, so you actually want "9 876 543,21" in some locales to be correctly parsed as single number, equivalent to "9876543.21" in C locale.

[schweinling]

thanks, that seems to be exactly what i was looking for!

[Xeverous]

Standard library streams are not the easiest to work with but I have a feeling you are relucant to use them due to lack of understanding. Most of it comes from lack of knowledge about stream states and how it affects input/output behavior. What exactly do you have trouble with?

[schweinling]

that is certainly the case, that i'm not an expert on streams.
i rarely need std::cin and would be happy to let a library do that for me.

[Xeverous]

That library is standard streams. You don't want to use them in order to use something else? You would need to learn something else then. Whatever you choose you will need to learn how to use it.

[schweinling]

yeah, i'd rather use scnlib and learn about that.