On Tue, Feb 11, 2025 at 1:45 PM Simon Schröder <dr.simon.schroeder_at_[hidden]>
wrote:
>
> On Tue, Feb 11, 2025 at 7:28 AM Pavel Vazharov <freakpv_at_[hidden]> wrote:
>>
>>
>>
>> On Mon, Feb 10, 2025 at 9:34 PM Simon Schröder via Std-Proposals <
std-proposals_at_[hidden]> wrote:
>> >
>> > Well, I agree that we don‘t necessarily need any extensions of
ostreams because we have std::format and std::print (though nothing
equivalent to std::print for writing to files directly). But, there not a
replacement for istreams, yet. Is there any proposal to replace istreams?
>> The std::print(ln) functions can write to files . Or maybe I
misunderstood you?
>
>
> Ah, I actually didn't know that. But why is it a C file descriptor, which
is not RAII?
There is another version
<https://en.cppreference.com/w/cpp/io/basic_ostream/print> which can write
to std::ostream but it comes from a different header.
>
> Still, we are missing something new for reading from files. Or did I miss
something else?
>>
>> >
>> > Simon
>> >
>> > On Feb 10, 2025, at 7:31 PM, Jeremy Rifkin via Std-Proposals <
std-proposals_at_[hidden]> wrote:
>> >
>> > 
>> > Hi,
>> > I would be surprised if this hasn’t been proposed before. Now that we
have std::format, I think it’s hard to make an argument for adding anything
formatting-related to iostreams.
>> >
>> > Cheers,
>> > Jeremy
>> >
>> > On Mon, Feb 10, 2025 at 12:01 Javier Estrada via Std-Proposals <
std-proposals_at_[hidden]> wrote:
>> >>
>> >> There is a manipulator gap to read/write integer numbers in binary.
As you well know, the standard manipulators are std::oct, std::dec,
std::hex, which is essentially a format flag onto ios_base::basefield.
>> >>
>> >> Having a dedicated manipulator would close that gap and would
eliminate the current "trick" of using std::bitset. The (abbreviated)
example in cppreference .com reads:
>> >>
>> >> #include <bitset>
>> >> #include <iostream>
>> >>
>> >> int main()
>> >> {
>> >> std::cout << "The number 42 in octal: " << std::oct << 42 <<
'\n'
>> >> << "The number 42 in decimal: " << std::dec << 42 <<
'\n'
>> >> << "The number 42 in hex: " << std::hex << 42 <<
'\n';
>> >>
>> >> // Note: there is no I/O manipulator that sets up a stream to
print out
>> >> // numbers in binary format (e.g. bin). If binary output is
necessary
>> >> // the std::bitset trick can be used:
>> >> std::cout << "The number 42 in binary: " << std::bitset<8>{42}
<< '\n';
>> >>
>> >> }
>> >>
>> >> With a std::bin manipulator:
>> >>
>> >> #include <iostream>
>> >> #include <sstream>
>> >>
>> >> int main()
>> >> {
>> >>
>> >> // This yields 101010
>> >> std::cout << "The number 42 in binary: " << std::bin << 42 <<
'\n';
>> >>
>> >> }
>> >>
>> >>
>> >> It would also take advantage of other manipulators, like std::setw
and std::setfill:
>> >>
>> >>
>> >> #include <iostream>
>> >> #include <sstream>
>> >>
>> >> int main()
>> >> {
>> >>
>> >> // This yields 00101010
>> >>
>> >> std::cout << std::setw(8) << std::setfill('0');
>> >>
>> >> std::cout << "The number 42 in binary: " << std::bin << 42 <<
'\n';
>> >>
>> >> }
>> >>
>> >>
>> >> Reading binary numbers would also be addressed by the input streams.
>> >>
>> >>
>> >> IF this proposal is considered, I see changes in:
>> >>
>> >> - A new bin flag in ios_base::basefield.
>> >>
>> >> - Support for the flag in ios_base::setf, ios_base::unsetf and
ios_base::flags member functions.
>> >>
>> >> - Creation of the manipulator (similar to other manipulators) for the
different char_traits
>> >>
>> >> - Support for binary parsing for input streams
>> >>
>> >> - Support for binary output for ostreams.
>> >>
>> >>
>> >> std::ios_base in cppreference.com:
>> >>
>> >> https://en.cppreference.com/w/cpp/io/ios_base
>> >>
>> >>
>> >> Integer I/O manipulators
>> >>
>> >> https://en.cppreference.com/w/cpp/io/manip/hex
>> >>
>> >>
>> >> Regards,
>> >>
>> >> —Javier
>> >>
>> >>
>> >>
>> >> --
>> >> Std-Proposals mailing list
>> >> Std-Proposals_at_[hidden]
>> >> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>> >
>> > --
>> > Std-Proposals mailing list
>> > Std-Proposals_at_[hidden]
>> > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>> >
>> > --
>> > Std-Proposals mailing list
>> > Std-Proposals_at_[hidden]
>> > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals