Hello,
in order to have correctly displayed output (before reading something from stdin),
I must call stdout.flush().
Sometimes, it's really annoying, especially when it is necessarry to call it 10 times.

For example:
write("Enter some string: ");
stdout.flush();
string a = readln();
write("And again please: ");
stdout.flush();
string b = readln();
...

Is there any way to prevent this?

On Tue, Dec 03, 2013 at 06:12:20PM +0100, Benji wrote:
> Hello,
> in order to have correctly displayed output (before reading
> something from stdin),
> I must call stdout.flush().
> Sometimes, it's really annoying, especially when it is necessarry to
> call it 10 times.
> 
> For example:
> write("Enter some string: ");
> stdout.flush();
> string a = readln();
> write("And again please: ");
> stdout.flush();
> string b = readln();
> ...
> 
> Is there any way to prevent this?

What about:

	void prompt(A...)(string fmt, A args)
	{
		writef(fmt, args);
		stdout.flush();
		return readln();
	}

	auto a = prompt("Enter your name: ");
	auto b = prompt("Enter your age: ").to!int;
	... // etc.


T

-- 
If you think you are too small to make a difference, try sleeping in a closed room with a mosquito. -- Jan van Steenbergen

On Tuesday, 3 December 2013 at 17:49:32 UTC, H. S. Teoh wrote:
> On Tue, Dec 03, 2013 at 06:12:20PM +0100, Benji wrote:
>> Hello,
>> in order to have correctly displayed output (before reading
>> something from stdin),
>> I must call stdout.flush().
>> Sometimes, it's really annoying, especially when it is necessarry to
>> call it 10 times.
>> 
>> For example:
>> write("Enter some string: ");
>> stdout.flush();
>> string a = readln();
>> write("And again please: ");
>> stdout.flush();
>> string b = readln();
>> ...
>> 
>> Is there any way to prevent this?
>
> What about:
>
> 	void prompt(A...)(string fmt, A args)
> 	{
> 		writef(fmt, args);
> 		stdout.flush();
> 		return readln();
> 	}
>
> 	auto a = prompt("Enter your name: ");
> 	auto b = prompt("Enter your age: ").to!int;
> 	... // etc.
>
>
> T

Thanks, I didn't think about that (I'm beginner)

On 12/03/2013 09:12 AM, Benji wrote:
> Hello,
> in order to have correctly displayed output (before reading something
> from stdin),
> I must call stdout.flush().

I am surprised that you need that. What is your platform?

Normally, stdin and stdout are "tied". Reading from stdin flushes stdout automatically.

Ali

On Tuesday, 3 December 2013 at 19:33:47 UTC, Ali Çehreli wrote:
> On 12/03/2013 09:12 AM, Benji wrote:
>> Hello,
>> in order to have correctly displayed output (before reading something
>> from stdin),
>> I must call stdout.flush().
>
> I am surprised that you need that. What is your platform?
>
> Normally, stdin and stdout are "tied". Reading from stdin flushes stdout automatically.
>
> Ali

I am using Xubuntu, 64bit, and GDC as compiler

On 12/03/2013 12:36 PM, Benji wrote:
> On Tuesday, 3 December 2013 at 19:33:47 UTC, Ali Çehreli wrote:
>> On 12/03/2013 09:12 AM, Benji wrote:
>>> Hello,
>>> in order to have correctly displayed output (before reading something
>>> from stdin),
>>> I must call stdout.flush().
>>
>> I am surprised that you need that. What is your platform?
>>
>> Normally, stdin and stdout are "tied". Reading from stdin flushes
>> stdout automatically.
>>
>> Ali
>
> I am using Xubuntu, 64bit, and GDC as compiler

I've known this to be the case for cin and cout of C++. So, I've been assuming that to be universally true. Apparently not for C and D behavior is based on C. I wish std.stdio gave us C++'s 'tie'.

Ali

P.S. This makes some of the examples at ddili.org incorrect as I never call flush. :-/

On Tuesday, 3 December 2013 at 20:36:22 UTC, Benji wrote:
> On Tuesday, 3 December 2013 at 19:33:47 UTC, Ali Çehreli wrote:
>> On 12/03/2013 09:12 AM, Benji wrote:
>>> Hello,
>>> in order to have correctly displayed output (before reading something
>>> from stdin),
>>> I must call stdout.flush().
>>
>> I am surprised that you need that. What is your platform?
>>
>> Normally, stdin and stdout are "tied". Reading from stdin flushes stdout automatically.
>>
>> Ali
>
> I am using Xubuntu, 64bit, and GDC as compiler

I haven't seen this behavior, though I haven't used GDC (debian is close enough right). This has been how I've retrieved user data:
https://github.com/JesseKPhillips/JPDLibs/blob/cmdln/cmdln/interact.d#L60

On Tuesday, 3 December 2013 at 20:36:22 UTC, Benji wrote:
> I am using Xubuntu, 64bit, and GDC as compiler

Any IDE? I've seen ide consoles buffer differently because the runtime sees the target as a pipe instead of a user-interactive terminal.

On Tuesday, 3 December 2013 at 21:47:19 UTC, Adam D. Ruppe wrote:
> On Tuesday, 3 December 2013 at 20:36:22 UTC, Benji wrote:
>> I am using Xubuntu, 64bit, and GDC as compiler
>
> Any IDE? I've seen ide consoles buffer differently because the runtime sees the target as a pipe instead of a user-interactive terminal.

I'm using using Eclipse Kepler Standard(4.3).
I tryied it via shell and everything worked fine also without stdout.flush().

On Tuesday, 3 December 2013 at 21:23:19 UTC, Ali Çehreli wrote:
> On 12/03/2013 12:36 PM, Benji wrote:
>> On Tuesday, 3 December 2013 at 19:33:47 UTC, Ali Çehreli wrote:
>>> On 12/03/2013 09:12 AM, Benji wrote:
>>>> Hello,
>>>> in order to have correctly displayed output (before reading something
>>>> from stdin),
>>>> I must call stdout.flush().
>>>
>>> I am surprised that you need that. What is your platform?
>>>
>>> Normally, stdin and stdout are "tied". Reading from stdin flushes
>>> stdout automatically.
>>>
>>> Ali
>>
>> I am using Xubuntu, 64bit, and GDC as compiler
>
> I've known this to be the case for cin and cout of C++. So, I've been assuming that to be universally true. Apparently not for C and D behavior is based on C. I wish std.stdio gave us C++'s 'tie'.
>
> Ali
>
> P.S. This makes some of the examples at ddili.org incorrect as I never call flush. :-/

The 'tie' is sometimes convenient, but it's not good in Unix style stdin/stout piping or similar situations with lots of simultaneous input and output.