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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: printf format specifier changes
Date: Mon, 06 Jul 2015 23:01:48 -0700
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Bartc <bc@freeuk.com> writes:
> On 06/07/2015 19:44, Richard Heathfield wrote:
[...]
> But the idea can be refined a bit more and it still couldn't be called a 
> mini-language.
>
>> There is prior art for an alternative system that allows precise format
>> control without requiring you to work /quite/ so hard on the types - the
>> iostream model used by C++. It may not be a good example, but it is at
>> least a horrible warning.
>
> It looks awful.

Tastes differ.  Personally, I have no esthetic problem with C++'s
use of overloaded >> and << operators for I/O; in that context,
I just don't think of them as shifts, and they do visually indicate
the direction in which the information flows.  (The same technique
couldn't be used in C without adding operator overloading to the
language.)

What I find annoying is that the constructs used to control formatting
(setting precision, width, base, etc) *change the state of the stream*.

In C, I can write:

    printf("x = 0x%x\n", x);

to print a value in hexadecimal, and it doesn't affect the next thing I
print.  In C++, if I write:

    std::cout << "x = 0x" << std::hex << x << "\n";

then the next integer I print will be in hexadecimal -- and if there's a
clean idiom to restore a stream to its previous state, I'm not familiar
with it.

If anybody designs a new formatted I/O system for C, please don't do
that.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"