/usr/share/doc/libbobcat4-dev/man/csv4180.3.html

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<h1 id="title">FBB::CSV4180(3bobcat)</h1>
<h2 id="author">CSV4180 convertor<br/>(libbobcat-dev_4.08.02-x.tar.gz)</h2>
<h2 id="date">2005-2017</h2>


<p>
<h2 >NAME</h2>FBB::CSV4180 - Converter for comma separated values
<p>
<h2 >SYNOPSIS</h2>
    <strong >#include &lt;bobcat/csv&gt;</strong><br/>
<p>
Linking option: <em >-lbobcat</em> 
<p>
<h2 >DESCRIPTION</h2>
<p>
Objects of the class <strong >CSV4180</strong> can be used to convert series of comma
separated values to the individual separated values (also called `fields'
below). The class implements RFC 4180
(cf. <a href="https://www.ietf.org/rfc/rfc4180.txt">https://www.ietf.org/rfc/rfc4180.txt</a>, section 2).
<p>
According to RFC 4180 lines contain comma separated values: comma separated
values on one line are processed together, as a series of values. The final
comma separated value on a line is not ended by a comma.
<p>
Comma separated values may be surrounded by double quotes. However, they
<em >must</em> be surrounded by double quotes in these cases:
    <ul>
    <li> if the values contain commas;
    <li> if the values contain double quotes (in which case the double quote
        is `escaped' by doubling it, e.g., <em >"a "" double quote"</em>);
    <li> if the values extend over multiple lines. E.g.,
        <pre>

"First line
second line"
    
</pre>

    </ul>
<p>
Comma separated values may be empty: the following line defines three
empty comma separated values:
        <pre>

,,
        
</pre>

    The first empty value starts at the beginning of the line, and continues
up to the first comma; the second empty value starts beyond the first comma
and continues up to the second comma; the third empty value starts beyond the
second comma, and continues up to the end of the line. If the line ends in
blank space characters then the third value isn't empty, but contains those
blank space characters.
<p>
By default, values are interpreted as strings. The <strong >CSV4180</strong> class also
offers facilities to ignore specific fields, or to ensure that they can be
converted to integral or floating point values. The second constructor (below)
expects a <em >std::string</em> argument defining how to interpret fields. Options
are: 
    <ul>
    <li> <em >I</em>:  the field must be convertible to an integral value;
    <li> <em >D</em>:  the field must be convertible to a floating point value;
    <li> <em >S</em>:  the field is a string: it is used as-is;
    <li> <em >X</em>:  the field is omitted from the final set of comma separated
        values. I.e., if a line contains three comma separated values, and the
        specification <em >"SXS"</em> is used then this results in two comma
        separated values: the first and third value of three comma separated
        values encountered on lines.
    <li> <em >-</em>:  synonym of <em >X</em>.
    </ul>
<p>
In addition, field specifications may contain blank spaces, which are
ignored. 
<p>
When processing comma separated values the first line may be considered a
<em >header</em> line. <em >X</em> specifications also apply to header lines, but
otherwise they merely consist of <em >S</em>-type fields. In addition, when
processing multiple input lines all non-header lines are made available in a
vector of vectors of fields, whereas the header line itself can be accessed
via a dedicated member (<em >header()</em>).
<p>
<h2 >NAMESPACE</h2>
    <strong >FBB</strong><br/>
    All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace <strong >FBB</strong>.
<p>
<h2 >INHERITS FROM</h2>
    -
<p>
<h2 >CONSTRUCTORS</h2>
    <ul>
    <li> <strong >explicit CSV4180(size_t nFields = 0, bool header = false, 
                    char fieldSep = ',')</strong>:<br/>
       The first parameter specifies the number of fields that must be
        present on input lines. When using the default value the number of
        fields encountered on the first line determines the number of fields
        that must be present on subsequent lines. If the second parameter is
        <em >true</em> then the first line is interpreted as the header line. The
        third parameter specifies the character separating the fields. By
        default it's a comma, but sometimes (not part of the RFC) a semicolon
        is used. By specifying <em >fieldSep</em> any character other than a comma
        can be used as field separator.
<p>
<li> <strong >explicit CSV4180(std::string const &amp;specs, bool header = false,
                    char fieldSep = ',')</strong>:<br/>
       The first parameter defines the number and types of the comma separated
        values on input lines. Specifications can be
        <blockquote >
            <ul>
            <li> <em >D</em>: the field must be convertible to a floating point
                value;
            <li> <em >I</em>: the field must be convertible to an integral value;
            <li> <em >S</em>: the field is left as-is, and can be retrieved as a
                <em >std::string</em>. 
            <li> <em >X</em> or <em >-</em>: the field is ignored and is not stored inside
                the <strong >CSV4180</strong> object.
            <li> blank space characters are ignored.
            </ul>
        </blockquote>
       An exception is thrown when encountering other than the abovementioned
        characters are encountered.
<p>
If <em >I</em> or <em >D</em> fields cannot be properly converted, or if a line
        contains too few or too many comma separated values the input stream's
        fail status is set.
<p>
The last two parameters are interpreted as the last two parameters of
        the previous constructor.
<p>
</ul><br/>
    The copy and move constructors are available.
<p>
<h2 >OVERLOADED OPERATORS</h2>
    <ul>
    <li> <strong >std::istream &amp;operator&gt;&gt;(std::istream &amp;in, CSV4180 &amp;csv)</strong>:<br/>
       One line of text is extracted from <em >in</em> and processed by the <em >csv</em>
        object. The <em >csv</em> object may or may not already contain converted
        comma separated values. When empty, the first line is processed
        according to the specifications provided to the <em >csv</em> object at
        construction time. Otherwise, the comma separated values on extracted
        lines must match the number and types of the fields, as specified by
        the <em >csv</em> object. When input lines do not match these specifications
        <em >in's</em> fail status is set.
    </ul><br/>
<p>
The copy and move assignment operators are available.
<p>
<h2 >MEMBER FUNCTIONS</h2>
    <ul>
    <li> <strong >void clear(size_t nFields = 0)</strong>:<br/>
       The internally stored data (referred to by the <em >data, header,</em> and
        <em >lastLine</em> members) are erased. By default, the required number of
        CSV fields is reset to 0, but can be set to a specific value by
        specifying a value for its <em >nFields</em> parameter.
<p>
<li> <strong >std::vector&lt;std::vector&lt;std::string&gt;&gt; const &amp;data() const</strong>:<br/>
       A reference to the vector of vectors of fields stored inside the
        <strong >CSV4180</strong> object is returned. The vector returned by <em >data</em> does
        not contain the header line. If a header line was requested it can be
        retrieved from the <em >header()</em> member.
<p>
<li> <strong >std::vector&lt;std::string&gt; const &amp;header() const</strong>:<br/>
       If the constructor's <em >header</em> parameter was specified as <em >true</em>
        then this member returns the fields encountered on the first line that
        was processed by the <em >read1</em> member. Otherwise, <em >header</em> returns
        a reference to an empty vector.
<p>
<li> <strong >std::string const &amp;lastLine() const</strong>:<br/>
       A reference to the last line that was successfully extracted from the
        input stream by the <em >read1</em> member is returned. So once the lines
        containing the comma separated values have been processed, the next
        line on the input stream can be obtained from this member.
<p>
<li> <strong >size_t nValues() const</strong>:<br/>
       After successfully calling <em >read1</em> for the first time this member
        returns the required number of comma separated values that must be
        encountered on subsequent input lines.
<p>
<li> <strong >size_t read(std::istream &amp;in, size_t nLines = 0)</strong>:<br/>
       By default, all lines of <em >in</em> are read and are processed by the
        <em >read1</em> member. By specifying a non-zero value for the <em >nLines</em>
        parameter the specified number of lines is read from <em >in</em>. 
        Reading stops once <em >in's</em> status is not <em >good</em>. When <em >nLines</em> is
        specified as zero, then <em >in's</em> status flags are cleared. The number
        of successfully processed lines is returned.
<p>
<li> <strong >std::istream &amp;read1(std::istream &amp;in)</strong>:<br/>
       One line is read from <em >in</em> and is parsed for its comma separated
        values. If parsing fails, <em >in's fail</em> status is set. After
        successfully calling <em >read1</em> for the first time all subsequent lines
        read by <em >read1</em> must have the same number of comma separated values
        as encountered when calling <em >read1</em> for the first time. The parsed
        fields are stored in a vector of <em >std::string</em> objects, and that
        vector is added to the vector of vectors of strings that is returned
        by the <em >data</em> member. 
<p>
<li> <strong >std::vector&lt;std::vector&lt;std::string&gt;&gt; release()</strong>:<br/>
       The vector of vectors of fields stored inside the <strong >CSV4180</strong> object is
        returned. After calling <em >release</em> the internally stored vector of
        fields is empty.  The vector returned by <em >data</em> does not contain the
        header line. If a header line was requested it can be retrieved from
        the <em >header()</em> member. Note that this member does not reset the
        number of expected fields for subsequently processed CSV-lines. If
        that's what you want, call <em >clear</em> after calling <em >release</em>.
<p>
</ul>
<p>
<h2 >EXAMPLE</h2>
    <pre>
#include &lt;iostream&gt;

#include &lt;bobcat/csv4180&gt;

using namespace std;
using namespace FBB;

int main(int argc, char **argv)
{

</pre>

<p>
<pre>
    CSV4180 csv;                    // this processes 'input'

</pre>

<p>
<pre>
    size_t nLines = csv.read(cin);

    cerr &lt;&lt; nLines &lt;&lt; " lines were read\n";
    if (not csv.header().empty())
    {
        cerr &lt;&lt; "header: " &lt;&lt; '\n';
        for (auto const &amp;field: csv.header())
            cerr &lt;&lt; "   `" &lt;&lt; field &lt;&lt; "'\n";
    }

    cerr &lt;&lt; "# CSV values: " &lt;&lt; csv.nValues() &lt;&lt; '\n';
    for (auto const &amp;line: csv.data())
    {
        cerr &lt;&lt; "Line:\n";
        for (auto const &amp;entry: line)
            cerr &lt;&lt; "   `" &lt;&lt; entry &lt;&lt; "'\n";
    }
}

</pre>

<p>
<h2 >FILES</h2>
    <em >bobcat/csv</em> - defines the class interface
<p>
<h2 >SEE ALSO</h2>
    <strong >bobcat</strong>(7)
<p>
<h2 >BUGS</h2>
    None Reported.
<p>

<h2 >DISTRIBUTION FILES</h2>
    <ul>
    <li> <em >bobcat_4.08.02-x.dsc</em>: detached signature;
    <li> <em >bobcat_4.08.02-x.tar.gz</em>: source archive;
    <li> <em >bobcat_4.08.02-x_i386.changes</em>: change log;
    <li> <em >libbobcat1_4.08.02-x_*.deb</em>: debian package holding the
            libraries;
    <li> <em >libbobcat1-dev_4.08.02-x_*.deb</em>: debian package holding the
            libraries, headers and manual pages;
    <li> <em >http://sourceforge.net/projects/bobcat</em>: public archive location;
    </ul>
<p>
<h2 >BOBCAT</h2>
    Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
<p>
<h2 >COPYRIGHT</h2>
    This is free software, distributed under the terms of the 
    GNU General Public License (GPL).
<p>
<h2 >AUTHOR</h2>
    Frank B. Brokken (<strong >f.b.brokken@rug.nl</strong>).
<p>
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libbobcat-dev 4.08.02-2build1 / usr / share / doc / libbobcat4-dev / man / csv4180.3.html
