http://d.puremagic.com/issues/show_bug.cgi?id=4656

           Summary: stdio.readf does not ignore white space
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody@puremagic.com
        ReportedBy: acehreli@yahoo.com


--- Comment #0 from Ali Cehreli <acehreli@yahoo.com> 2010-08-16 14:11:35 PDT ---
This makes it very difficult to read values. We can't retire din.readf before fixing this.

import std.stdio;

void main()
{
    int i, j;
    readf("%s", &i);
    readf("%s", &j);
}

Run the program and provide the following as input:

42 43

The program terminates with

std.conv.ConvError: std.conv(1070): Can't convert value
`LockingTextReader(File(807637C),  )' of type LockingTextReader to type int

The reason is the white space.

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Andrei Alexandrescu <andrei@metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei@metalanguage.com
         AssignedTo|nobody@puremagic.com        |andrei@metalanguage.com


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--- Comment #1 from Andrei Alexandrescu <andrei@metalanguage.com> 2011-05-09 09:18:02 PDT ---
This is by design. The example works when modified as follows:

import std.stdio;

void main()
{
    int i, j;
    readf("%s", &i);
    readf(" %s", &j);
}

The space before the second parameter tells readf to read and skip all whitespace before attempting conversion.

I've implemented readf to be a fair amount more Nazi about whitespace than scanf in an attempt to improve its precision. Scanf has been famously difficult to use for complex input parsing and validation, and I attribute some of that to its laissez-faire attitude toward whitespace. I'd be glad to relax some of readf's insistence on precise whitespace handling if there's enough evidence that that serves most of our users. I personally believe that the current behavior (strict by default, easy to relax) is best.

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Ali Cehreli <acehreli@yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |INVALID


--- Comment #2 from Ali Cehreli <acehreli@yahoo.com> 2011-05-09 10:42:43 PDT ---
My apologies for forgetting about this bug report. I have since then replaced din and dout with stdin and stdout in D.ershane. The nazi whitespace behaviour worked correctly and consistently in all of the examples.

Thank you,
Ali

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Andrei Alexandrescu <andrei@metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |


--- Comment #3 from Andrei Alexandrescu <andrei@metalanguage.com> 2011-05-09 11:27:57 PDT ---
Let's keep it opened until the error message is fixed.

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SomeDude <lovelydear@mailmetrash.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lovelydear@mailmetrash.com


--- Comment #4 from SomeDude <lovelydear@mailmetrash.com> 2012-04-21 15:22:11 PDT ---
The original test case now produces this message:

PS E:\DigitalMars\dmd2\samples> rdmd bug.d
456 45646
std.conv.ConvException@E:\DigitalMars\dmd2\windows\bin\..\..\src\phobos\std\conv.d(1779):
Unexpected ' ' when converting from type LockingTextReader to type int

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