Hi Garrett

Many thanks for the reply with link.

std::format could be good good, I hadn't heard. Currently I had always
needed to use my own variadic std::string str_sprintf().
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0645r9.html#Syntax

Saw this
std::string s = std::format("{:s}", true);

It looks like different syntax to printf % style is being used. Don't
think that is ideal...
But at least bool is in..

Cheers, Jonny





On 20/07/2019 22:24, Garrett May via Std-Proposals wrote:
> Hi Jonny,
>
> With respect to std::to_string, please see a reference to it here:
> https://en.cppreference.com/w/cpp/string/basic_string/to_string
>
> std::to_string appears to be defined specifically for primitive
> numeric types that match up to using sprintf and a format specifier. I
> don't think that std::to_string(bool) would be suitable, as it does
> not have a format specifier like the others. And there is also the
> possibility that when converting a bool to a string that the user
> genuinely want '0' or '1' to be produced, as they may be trying to
> handle the result as data.
>
> As Jake said, there is a format library coming out for C++20. That
> sounds like a more desirable way to handle this problem, as like I
> mentioned, choosing how one wants a bool to be represented textually
> is similar to how one would want a float or a double represented
> textually.
>
> Regards,
>
> Garrett
>
> On Sat, 20 Jul 2019, 21:39 Jonny Grant via Std-Proposals,
> <std-proposals_at_[hidden]
> <mailto:std-proposals_at_[hidden]>> wrote:
>
> Hi Garrett
>
> Many thanks for your reply.
>
> Yes, I see std::boolalpha sets an I/O flag.. but seems a bit of a
> long way to get it into a string, I'd need to use in conjunction
> with std::istringstream to get a string...
>
> I wanted to do something like this example:
>
> *Idea*
> std::string fmt(const std::string header, bool b)
> {
> return header + " " + std::to_string(b) + " set";
> }
>
> *How I would do now*
> As his doesn't work, I'd have it at present as:
> std::string fmt(const std::string header, bool b)
> {
> return header + " " + b?"true":"false" + " set";
> }
>
>
> Regards, Jonny
>
>
> On 20/07/2019 21:21, Garrett May via Std-Proposals wrote:
>> std::boolalpha is already available:
>>
>> int main(){
>> bool const a = true;
>> std::cout << std::boolalpha << a << std::endl;
>> }
>>
>> My gut instinct here is that one is supposed to control how one
>> wants data to be printed out, in the same way as how float/double
>> precision is done.
>>
>>
>> On Sat, 20 Jul 2019, 21:16 Jonny Grant via Std-Proposals,
>> <std-proposals_at_[hidden]
>> <mailto:std-proposals_at_[hidden]>> wrote:
>>
>> Hello
>>
>> Could std::string to_string(bool value); be added? Currently
>> it outputs
>> as a number due to the implicit conversion to int?
>> Feel it would have been more appropriate as "true" or "false".
>>
>> http://www.cplusplus.com/reference/string/to_string/
>>
>> $ g++-8 -Wall -o to_string to_string.cpp
>> $ ./to_string
>> 1
>>
>>
>>
>> // g++-8 -Wall -o to_string to_string.cpp
>> #include <string>
>> #include <iostream>
>> int main()
>> {
>> const bool a = true;
>> const std::string b(std::to_string(a));
>> std::cout << b << std::endl;
>> }
>>
>> Cheers, Jonny
>>
>>
>>
>> .
>>
>>
>> --
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>>
>>
>
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