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### 118. `basic_istream` uses nonexistent `num_get` member functions

Section: 31.7.5.3.2 [istream.formatted.arithmetic] Status: CD1 Submitter: Matt Austern Opened: 1998-11-20 Last modified: 2016-01-28

Priority: Not Prioritized

View all other issues in [istream.formatted.arithmetic].

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Discussion:

Formatted input is defined for the types `short`, `unsigned short`, `int`, `unsigned int`, `long`, `unsigned long`, `float`, `double`, `long double`, `bool`, and `void*`. According to section 27.6.1.2.2, formatted input of a value `x` is done as if by the following code fragment:

    typedef num_get< charT,istreambuf_iterator<charT,traits> > numget;
    iostate err = 0;
    use_facet< numget >(loc).get(*this, 0, *this, err, val);
    setstate(err);

According to section 30.4.3.2.2 [facet.num.get.members], however, `num_get<>::get()` is only overloaded for the types `bool`, `long`, `unsigned short`, `unsigned int`, `unsigned long`, `unsigned long`, `float`, `double`, `long double`, and `void*`. Comparing the lists from the two sections, we find that 27.6.1.2.2 is using a nonexistent function for types `short` and `int`.

Proposed resolution:

In 31.7.5.3.2 [istream.formatted.arithmetic] Arithmetic Extractors, remove the two lines (1st and 3rd) which read:

>     operator>>(short& val);
>     ...
>     operator>>(int& val);

And add the following at the end of that section (27.6.1.2.2) :

>     operator>>(short& val);

> The conversion occurs as if performed by the following code fragment (using the same notation as for the preceding code fragment):

>       typedef num_get< charT,istreambuf_iterator<charT,traits> > numget;
>       iostate err = 0;
>       long lval;
>       use_facet< numget >(loc).get(*this, 0, *this, err, lval);
>             if (err == 0
>                     && (lval < numeric_limits<short>::min() || numeric_limits<short>::max() < lval))
>                     err = ios_base::failbit;
>       setstate(err);

>     operator>>(int& val);

> The conversion occurs as if performed by the following code fragment (using the same notation as for the preceding code fragment):

>       typedef num_get< charT,istreambuf_iterator<charT,traits> > numget;
>       iostate err = 0;
>       long lval;
>       use_facet< numget >(loc).get(*this, 0, *this, err, lval);
>             if (err == 0
>                     && (lval < numeric_limits<int>::min() || numeric_limits<int>::max() < lval))
>                     err = ios_base::failbit;
>       setstate(err);

[Post-Tokyo: PJP provided the above wording.]