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<link title="Weak" rel="Chapter" href="Weak.html"><title>Scanf</title>
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<center><h1>Module <a href="type_Scanf.html">Scanf</a></h1></center>
<br>
<pre><span class="keyword">module</span> Scanf: <code class="type">sig end</code></pre><div class="info">
Formatted input functions.<br>
</div>
<hr width="100%">
<pre><span class="keyword">module</span> <a href="Scanf.Scanning.html">Scanning</a>: <code class="type">sig end</code></pre><div class="info">
Scanning buffers.
</div>
<pre><span class="keyword">exception</span> <a name="EXCEPTIONScan_failure"></a>Scan_failure <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info">
The exception that formatted input functions raise when the input
cannot be read according to the given format.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALbscanf"></a>bscanf : <code class="type"><a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a> -> ('a, <a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a>, 'b) format -> 'a -> 'b</code></pre><div class="info">
<code class="code">bscanf ib format f</code> reads tokens from the scanning buffer <code class="code">ib</code> according
to the format string <code class="code">format</code>, converts these tokens to values, and
applies the function <code class="code">f</code> to these values.
The result of this application of <code class="code">f</code> is the result of the whole construct.
<p>
Raise <code class="code"><span class="constructor">Scanf</span>.<span class="constructor">Scan_failure</span></code> if the given input does not match the format.
<p>
Raise <code class="code"><span class="constructor">Failure</span></code> if a conversion to a number is not possible.
<p>
Raise <code class="code"><span class="constructor">End_of_file</span></code> if the end of input is encountered while scanning
and the input matches the given format so far.
<p>
The format is a character string which contains three types of
objects:<ul>
<li>plain characters, which are simply matched with the
characters of the input,</li>
<li>conversion specifications, each of which causes reading and
conversion of one argument for <code class="code">f</code>,</li>
<li>scanning indications to specify boundaries of tokens.</li>
</ul>
Among plain characters the space character (ASCII code 32) has a
special meaning: it matches ``whitespace'', that is any number of tab,
space, newline and carriage return characters. Hence, a space in the format
matches any amount of whitespace in the input.
<p>
Conversion specifications consist in the <code class="code">%</code> character, followed
by optional field width, followed by one or two conversion
characters. The conversion characters and their meanings are:<ul>
<li><code class="code">d</code>: reads an optionally signed decimal integer.</li>
<li><code class="code">i</code>: reads an optionally signed integer
(usual input formats for hexadecimal (<code class="code">0x[d]+</code> and <code class="code">0<span class="constructor">X</span>[d]+</code>),
octal (<code class="code">0o[d]+</code>), and binary <code class="code">0b[d]+</code> notations are understood).</li>
<li><code class="code">u</code>: reads an unsigned decimal integer.</li>
<li><code class="code">x</code> or <code class="code"><span class="constructor">X</span></code>: reads an unsigned hexadecimal integer.</li>
<li><code class="code">o</code>: reads an unsigned octal integer.</li>
<li><code class="code">s</code>: reads a string argument (by default strings end with a space).</li>
<li><code class="code"><span class="constructor">S</span></code>: reads a delimited string argument (delimiters and special
escaped characters follow the lexical conventions of Caml).</li>
<li><code class="code">c</code>: reads a single character.</li>
<li><code class="code"><span class="constructor">C</span></code>: reads a single delimited character (delimiters and special
escaped characters follow the lexical conventions of Caml).</li>
<li><code class="code">f</code>, <code class="code">e</code>, <code class="code"><span class="constructor">E</span></code>, <code class="code">g</code>, <code class="code"><span class="constructor">G</span></code>: reads an optionally signed floating-point number
in decimal notation, in the style <code class="code">dddd.ddd e/<span class="constructor">E</span>+-dd</code>.</li>
<li><code class="code">b</code>: reads a boolean argument (<code class="code"><span class="keyword">true</span></code> or <code class="code"><span class="keyword">false</span></code>).</li>
<li><code class="code">ld</code>, <code class="code">li</code>, <code class="code">lu</code>, <code class="code">lx</code>, <code class="code">lX</code>, <code class="code">lo</code>: reads an <code class="code">int32</code> argument to
the format specified by the second letter (decimal, hexadecimal, etc).</li>
<li><code class="code">nd</code>, <code class="code">ni</code>, <code class="code">nu</code>, <code class="code">nx</code>, <code class="code">nX</code>, <code class="code">no</code>: reads a <code class="code">nativeint</code> argument to
the format specified by the second letter.</li>
<li><code class="code"><span class="constructor">Ld</span></code>, <code class="code"><span class="constructor">Li</span></code>, <code class="code"><span class="constructor">Lu</span></code>, <code class="code"><span class="constructor">Lx</span></code>, <code class="code"><span class="constructor">LX</span></code>, <code class="code"><span class="constructor">Lo</span></code>: reads an <code class="code">int64</code> argument to
the format specified by the second letter.</li>
<li><code class="code">[ range ]</code>: reads characters that matches one of the characters
mentioned in the range of characters <code class="code">range</code> (or not mentioned in
it, if the range starts with <code class="code">^</code>). Returns a <code class="code">string</code> that can be
empty, if no character in the input matches the range.</li>
<li><code class="code"><span class="constructor">N</span></code>: applies <code class="code">f</code> to the number of characters read so far.</li>
<li><code class="code">%</code>: matches one <code class="code">%</code> character in the input.</li>
</ul>
The field widths are composed of an optional integer literal
indicating the maximal width of the token to read.
For instance, <code class="code">%6d</code> reads an integer, having at most 6 decimal digits;
and <code class="code">%4f</code> reads a float with 4 characters.
<p>
Scanning indications appear just after string conversions <code class="code">s</code> and
<code class="code">[ range ]</code> to delimit the end of the token. A scanning
indication is introduced by a <code class="code">@</code> character, followed by some
constant character <code class="code">c</code>. It means that the string token should end
just before the next matching <code class="code">c</code>. If no <code class="code">c</code> character is
encountered, the string token spreads as much as possible.
For instance, <code class="code"><span class="string">"%s@\t"</span></code> reads a string up to the next tabulation
character. If a scanning indication <code class="code">@c</code> does not follow a
string conversion, it is ignored and treated as a plain <code class="code">c</code>
character.
<p>
Note: the <code class="code">scanf</code> facility is not intended for heavy duty
lexical analysis and parsing. If it appears not expressive
enough for your needs, several alternative exists: regular expressions
(module <code class="code"><span class="constructor">Str</span></code>), stream parsers, <code class="code">ocamllex</code>-generated lexers,
<code class="code">ocamlyacc</code>-generated parsers.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALfscanf"></a>fscanf : <code class="type"><a href="Pervasives.html#TYPEin_channel">Pervasives.in_channel</a> -> ('a, <a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a>, 'b) format -> 'a -> 'b</code></pre><div class="info">
Same as <a href="Scanf.html#VALbscanf"><code class="code"><span class="constructor">Scanf</span>.bscanf</code></a>, but inputs from the given channel.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALsscanf"></a>sscanf : <code class="type">string -> ('a, <a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a>, 'b) format -> 'a -> 'b</code></pre><div class="info">
Same as <a href="Scanf.html#VALbscanf"><code class="code"><span class="constructor">Scanf</span>.bscanf</code></a>, but inputs from the given string.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALscanf"></a>scanf : <code class="type">('a, <a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a>, 'b) format -> 'a -> 'b</code></pre><div class="info">
Same as <a href="Scanf.html#VALbscanf"><code class="code"><span class="constructor">Scanf</span>.bscanf</code></a>, but inputs from <code class="code">stdin</code>
(the standard input channel).<br>
</div>
<pre><span class="keyword">val</span> <a name="VALkscanf"></a>kscanf : <code class="type"><a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a> -><br> (<a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a> -> exn -> 'a) -><br> ('b, <a href="Scanf.Scanning.html#TYPEscanbuf">Scanning.scanbuf</a>, 'a) format -> 'b -> 'a</code></pre><div class="info">
Same as <a href="Scanf.html#VALbscanf"><code class="code"><span class="constructor">Scanf</span>.bscanf</code></a>, but takes an additional function argument
<code class="code">ef</code> that is called in case of error: if the scanning process or
some conversion fails, the scanning function aborts and applies the
error handling function <code class="code">ef</code> to the scanning buffer and the
exception that aborted evaluation.<br>
</div>
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