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<H1> A.8.5 Direct Input-Output Operations</H1>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> The operations available for direct input and
output are described in this subclause. The exception Status_Error is
propagated if any of these operations is attempted for a file that is
not open. </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Read(File : <B>in</B> File_Type; Item : <B>out</B> Element_Type;<BR>
From : <B>in</B> Positive_Count);<BR>
<B>procedure</B> Read(File : <B>in</B> File_Type; Item : <B>out</B> Element_Type);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="CodeIndented">Operates on a file of mode In_File or Inout_File.
In the case of the first form, sets the current index of the given file
to the index value given by the parameter From. Then (for both forms)
returns, in the parameter Item, the value of the element whose position
in the given file is specified by the current index of the file; finally,
increases the current index by one.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">The exception
Mode_Error is propagated if the mode of the given file is Out_File. The
exception End_Error is propagated if the index to be used exceeds the
size of the external file. The exception Data_Error can be propagated
if the element read cannot be interpreted as a value of the subtype Element_Type
(see <A HREF="AA-A-13.html">A.13</A>).</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Write(File : <B>in</B> File_Type; Item : <B>in</B> Element_Type;<BR>
To : <B>in</B> Positive_Count);<BR>
<B>procedure</B> Write(File : <B>in</B> File_Type; Item : <B>in</B> Element_Type);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="CodeIndented">Operates on a file of mode Inout_File or Out_File.
In the case of the first form, sets the index of the given file to the
index value given by the parameter To. Then (for both forms) gives the
value of the parameter Item to the element whose position in the given
file is specified by the current index of the file; finally, increases
the current index by one.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">The exception
Mode_Error is propagated if the mode of the given file is In_File. The
exception Use_Error is propagated if the capacity of the external file
is exceeded.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Set_Index(File : <B>in</B> File_Type; To : <B>in</B> Positive_Count);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>9</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">Operates on a
file of any mode. Sets the current index of the given file to the given
index value (which may exceed the current size of the file).</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>10</FONT></DIV>
<DIV Class="Examples"><TT><B>function</B> Index(File : <B>in</B> File_Type) <B>return</B> Positive_Count;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>11</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">Operates on a
file of any mode. Returns the current index of the given file.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>12</FONT></DIV>
<DIV Class="Examples"><TT><B>function</B> Size(File : <B>in</B> File_Type) <B>return</B> Count;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>13</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">Operates on a
file of any mode. Returns the current size of the external file that
is associated with the given file.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>14</FONT></DIV>
<DIV Class="Examples"><TT><B>function</B> End_Of_File(File : <B>in</B> File_Type) <B>return</B> Boolean;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>15</FONT></DIV>
<DIV Class="CodeIndented">Operates on a file of mode In_File or Inout_File.
Returns True if the current index exceeds the size of the external file;
otherwise returns False.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>16</FONT></DIV>
<DIV Class="CodeIndented">The exception Mode_Error is propagated if the
mode of the given file is Out_File.</DIV>
<DIV Class="NotesHeader"><FONT SIZE=-1>NOTES</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>17</FONT></DIV>
<DIV Class="Notes"><FONT SIZE=-1>20 Append_File mode is not
supported for the generic package Direct_IO. </FONT></DIV>
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