labs/lab10/inlab-skeleton.cpp.html

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<pre><tt><i><font color="#9A1900">// This program is the skeleton code for the lab 10 in-lab.</font></i>
<i><font color="#9A1900">// It uses C++ streams for the file input,</font></i>
<i><font color="#9A1900">// and just prints out the data when read in from the file.</font></i>

<b><font color="#000080">#include</font></b> <font color="#FF0000">&lt;iostream&gt;</font>
<b><font color="#000080">#include</font></b> <font color="#FF0000">&lt;fstream&gt;</font>
<b><font color="#000080">#include</font></b> <font color="#FF0000">&lt;sstream&gt;</font>
<b><font color="#000080">#include</font></b> <font color="#FF0000">&lt;cstdlib&gt;</font>
<b><font color="#0000FF">using</font></b> <b><font color="#0000FF">namespace</font></b> std<font color="#990000">;</font>

<i><font color="#9A1900">// main(): we want to use parameters</font></i>
<font color="#009900">int</font> <b><font color="#000000">main</font></b> <font color="#990000">(</font><font color="#009900">int</font> argc<font color="#990000">,</font> <font color="#009900">char</font><font color="#990000">**</font> argv<font color="#990000">)</font> <font color="#FF0000">{</font>
    <i><font color="#9A1900">// verify the correct number of parameters</font></i>
    <b><font color="#0000FF">if</font></b> <font color="#990000">(</font>argc <font color="#990000">!=</font> <font color="#993399">2</font><font color="#990000">)</font> <font color="#FF0000">{</font>
        cout <font color="#990000">&lt;&lt;</font> <font color="#FF0000">"Must supply the input file name as the only parameter"</font> <font color="#990000">&lt;&lt;</font> endl<font color="#990000">;</font>
        <b><font color="#000000">exit</font></b><font color="#990000">(</font><font color="#993399">1</font><font color="#990000">);</font>
    <font color="#FF0000">}</font>

    <i><font color="#9A1900">// attempt to open the supplied file</font></i>
    <i><font color="#9A1900">// must be opened in binary mode as otherwise trailing whitespace is discarded</font></i>
    <font color="#008080">ifstream</font> <b><font color="#000000">file</font></b><font color="#990000">(</font>argv<font color="#990000">[</font><font color="#993399">1</font><font color="#990000">],</font> ifstream<font color="#990000">::</font>binary<font color="#990000">);</font>
    <i><font color="#9A1900">// report any problems opening the file and then exit</font></i>
    <b><font color="#0000FF">if</font></b> <font color="#990000">(!</font>file<font color="#990000">.</font><b><font color="#000000">is_open</font></b><font color="#990000">())</font> <font color="#FF0000">{</font>
        cout <font color="#990000">&lt;&lt;</font> <font color="#FF0000">"Unable to open file '"</font> <font color="#990000">&lt;&lt;</font> argv<font color="#990000">[</font><font color="#993399">1</font><font color="#990000">]</font> <font color="#990000">&lt;&lt;</font> <font color="#FF0000">"'."</font> <font color="#990000">&lt;&lt;</font> endl<font color="#990000">;</font>
        <b><font color="#000000">exit</font></b><font color="#990000">(</font><font color="#993399">2</font><font color="#990000">);</font>
    <font color="#FF0000">}</font>

    <i><font color="#9A1900">// read in the first section of the file: the prefix codes</font></i>
    <b><font color="#0000FF">while</font></b> <font color="#990000">(</font><b><font color="#0000FF">true</font></b><font color="#990000">)</font> <font color="#FF0000">{</font>
        <font color="#008080">string</font> character<font color="#990000">,</font> prefix<font color="#990000">;</font>
        <i><font color="#9A1900">// read in the first token on the line</font></i>
        file <font color="#990000">&gt;&gt;</font> character<font color="#990000">;</font>

        <i><font color="#9A1900">// did we hit the separator?</font></i>
        <b><font color="#0000FF">if</font></b> <font color="#990000">(</font>character<font color="#990000">[</font><font color="#993399">0</font><font color="#990000">]</font> <font color="#990000">==</font> <font color="#FF0000">'-'</font> <font color="#990000">&amp;&amp;</font> character<font color="#990000">.</font><b><font color="#000000">length</font></b><font color="#990000">()</font> <font color="#990000">&gt;</font> <font color="#993399">1</font><font color="#990000">)</font> <font color="#FF0000">{</font>
            <b><font color="#0000FF">break</font></b><font color="#990000">;</font>
        <font color="#FF0000">}</font>

        <i><font color="#9A1900">// check for space</font></i>
        <b><font color="#0000FF">if</font></b> <font color="#990000">(</font>character <font color="#990000">==</font> <font color="#FF0000">"space"</font><font color="#990000">)</font> <font color="#FF0000">{</font>
            character <font color="#990000">=</font> <font color="#FF0000">" "</font><font color="#990000">;</font>
        <font color="#FF0000">}</font>

        <i><font color="#9A1900">// read in the prefix code</font></i>
        file <font color="#990000">&gt;&gt;</font> prefix<font color="#990000">;</font>
        <i><font color="#9A1900">// do something with the prefix code</font></i>
        cout <font color="#990000">&lt;&lt;</font> <font color="#FF0000">"character '"</font> <font color="#990000">&lt;&lt;</font> character <font color="#990000">&lt;&lt;</font> <font color="#FF0000">"' has prefix code '"</font> <font color="#990000">&lt;&lt;</font> prefix <font color="#990000">&lt;&lt;</font> <font color="#FF0000">"'"</font> <font color="#990000">&lt;&lt;</font> endl<font color="#990000">;</font>
    <font color="#FF0000">}</font>

    <i><font color="#9A1900">// read in the second section of the file: the encoded message</font></i>
    <font color="#008080">stringstream</font> sstm<font color="#990000">;</font>
    <b><font color="#0000FF">while</font></b> <font color="#990000">(</font><b><font color="#0000FF">true</font></b><font color="#990000">)</font> <font color="#FF0000">{</font>
        <font color="#008080">string</font> bits<font color="#990000">;</font>
        <i><font color="#9A1900">// read in the next set of 1's and 0's</font></i>
        file <font color="#990000">&gt;&gt;</font> bits<font color="#990000">;</font>
        <i><font color="#9A1900">// check for the separator</font></i>
        <b><font color="#0000FF">if</font></b> <font color="#990000">(</font>bits<font color="#990000">[</font><font color="#993399">0</font><font color="#990000">]</font> <font color="#990000">==</font> <font color="#FF0000">'-'</font><font color="#990000">)</font> <font color="#FF0000">{</font>
            <b><font color="#0000FF">break</font></b><font color="#990000">;</font>
        <font color="#FF0000">}</font>
        <i><font color="#9A1900">// add it to the stringstream</font></i>
        sstm <font color="#990000">&lt;&lt;</font> bits<font color="#990000">;</font>
    <font color="#FF0000">}</font>

    <font color="#008080">string</font> allbits <font color="#990000">=</font> sstm<font color="#990000">.</font><b><font color="#000000">str</font></b><font color="#990000">();</font>
    <i><font color="#9A1900">// at this point, all the bits are in the 'allbits' string</font></i>
    cout <font color="#990000">&lt;&lt;</font> <font color="#FF0000">"All the bits: "</font> <font color="#990000">&lt;&lt;</font> allbits <font color="#990000">&lt;&lt;</font> endl<font color="#990000">;</font>
    <i><font color="#9A1900">// close the file before exiting</font></i>
    file<font color="#990000">.</font><b><font color="#000000">close</font></b><font color="#990000">();</font>

    <b><font color="#0000FF">return</font></b> <font color="#993399">0</font>
<font color="#FF0000">}</font>
</tt></pre>
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