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📄 hashes.mht

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color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>push</FONT><FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@common</FONT>, $_<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#ffa500>if</FONT> <FONT color=3D#ff7f50>exists</FONT> <FONT =
color=3D#cdcd00>$hash2</FONT><FONT color=3D#00ffff>{</FONT>$_<FONT =
color=3D#00ffff>};</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe># </FONT><FONT color=3D#cdad00>@common</FONT><FONT =
color=3D#bebebe> now contains common keys
#-----------------------------
</FONT><FONT color=3D#ffa500>my</FONT> <FONT =
color=3D#cdad00>@this_not_that</FONT> =3D <FONT =
color=3D#00ffff>();</FONT>
<FONT color=3D#ffa500>foreach</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#ff7f50>keys</FONT> <FONT color=3D#cdcd00>%hash1</FONT><FONT =
color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>push</FONT><FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@this_not_that</FONT>, $_<FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#ffa500>unless</FONT> <FONT color=3D#ff7f50>exists</FONT> =
<FONT color=3D#cdcd00>$hash2</FONT><FONT color=3D#00ffff>{</FONT>$_<FONT =
color=3D#00ffff>};</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
# </FONT><FONT color=3D#cdcd00>%food_color</FONT><FONT color=3D#bebebe> =
per the introduction
</FONT>
<FONT color=3D#bebebe># </FONT><FONT =
color=3D#cdcd00>%citrus_color</FONT><FONT color=3D#bebebe> is a hash =
mapping citrus food name to its color.
</FONT><FONT color=3D#cdcd00>%citrus_color</FONT> =3D <FONT =
color=3D#00ffff>(</FONT> <FONT color=3D#00cd00>Lemon</FONT>  =3D&gt; =
<FONT color=3D#00cd00>"yellow"</FONT>,
                  <FONT color=3D#00cd00>Orange</FONT> =3D&gt; <FONT =
color=3D#00cd00>"orange"</FONT>,
                  <FONT color=3D#00cd00>Lime</FONT>   =3D&gt; <FONT =
color=3D#00cd00>"green"</FONT> <FONT color=3D#00ffff>);</FONT>

<FONT color=3D#bebebe># build up a list of non-citrus foods
</FONT><FONT color=3D#cdad00>@non_citrus</FONT> =3D <FONT =
color=3D#00ffff>();</FONT>

<FONT color=3D#ffa500>foreach</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#ff7f50>keys</FONT> <FONT =
color=3D#cdcd00>%food_color</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>push</FONT> <FONT =
color=3D#00ffff>(</FONT><FONT color=3D#cdad00>@non_citrus</FONT>, =
$_<FONT color=3D#00ffff>)</FONT> <FONT color=3D#ffa500>unless</FONT> =
<FONT color=3D#ff7f50>exists</FONT> <FONT =
color=3D#cdcd00>$citrus_color</FONT><FONT =
color=3D#00ffff>{</FONT>$_<FONT color=3D#00ffff>};</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN268>Hashing References</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>Tie::RefHash</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#ff7f50>tie</FONT> <FONT color=3D#cdcd00>%hash</FONT>, =
<FONT color=3D#00cd00>"Tie::RefHash"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe># you may now use references as the keys to =
</FONT><FONT color=3D#cdcd00>%hash</FONT><FONT color=3D#bebebe>
#-----------------------------
# Class::Somewhere=3DHASH(0x72048)
#</FONT><FONT color=3D#43cd80> </FONT><FONT color=3D#bebebe>
# ARRAY(0x72048)
#-----------------------------
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>Tie::RefHash</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>IO::File</FONT><FONT color=3D#00ffff>;</FONT>

<FONT color=3D#ff7f50>tie</FONT> <FONT color=3D#cdcd00>%name</FONT>, =
<FONT color=3D#00cd00>"Tie::RefHash"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>foreach</FONT> <FONT =
color=3D#9ac0cd>$filename</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#00cd00>"/etc/termcap"</FONT>, <FONT =
color=3D#00cd00>"/vmunix"</FONT>, <FONT =
color=3D#00cd00>"/bin/cat"</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    $fh =3D IO::File-&gt;new<FONT color=3D#00ffff>(</FONT><FONT =
color=3D#00cd00>"&lt; $filename"</FONT><FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>next</FONT><FONT =
color=3D#00ffff>;</FONT>
    <FONT color=3D#cdcd00>$name</FONT><FONT =
color=3D#00ffff>{</FONT>$fh<FONT color=3D#00ffff>}</FONT> =3D =
$filename<FONT color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"open files: =
"</FONT>, <FONT color=3D#98fb98>join</FONT><FONT =
color=3D#00ffff>(</FONT><FONT color=3D#00cd00>", "</FONT>, <FONT =
color=3D#98fb98>values</FONT> <FONT color=3D#cdcd00>%name</FONT><FONT =
color=3D#00ffff>)</FONT>, <FONT color=3D#00cd00>"\n"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>foreach</FONT> <FONT color=3D#9ac0cd>$file</FONT> =
<FONT color=3D#00ffff>(</FONT><FONT color=3D#ff7f50>keys</FONT> <FONT =
color=3D#cdcd00>%name</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#98fb98>seek</FONT><FONT =
color=3D#00ffff>(</FONT>$file, <FONT color=3D#cdcd00>0</FONT>, <FONT =
color=3D#cdcd00>2</FONT><FONT color=3D#00ffff>);</FONT>      <FONT =
color=3D#bebebe># seek to the end
</FONT>    <FONT color=3D#ff7f50>printf</FONT><FONT =
color=3D#00ffff>(</FONT><FONT color=3D#00cd00>"</FONT><FONT =
color=3D#cdcd00>%s</FONT><FONT color=3D#00cd00> is </FONT><FONT =
color=3D#cdcd00>%d</FONT><FONT color=3D#00cd00> bytes long.\n"</FONT>, =
<FONT color=3D#cdcd00>$name</FONT><FONT =
color=3D#00ffff>{</FONT>$file<FONT color=3D#00ffff>}</FONT>, <FONT =
color=3D#98fb98>tell</FONT><FONT color=3D#00ffff>(</FONT>$file<FONT =
color=3D#00ffff>));</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN271>Presizing a Hash</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
# presize </FONT><FONT color=3D#cdcd00>%hash</FONT><FONT =
color=3D#bebebe> to $num
</FONT><FONT color=3D#ff7f50>keys</FONT><FONT =
color=3D#00ffff>(</FONT><FONT color=3D#cdcd00>%hash</FONT><FONT =
color=3D#00ffff>)</FONT> =3D $num<FONT color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
# will have 512 users in </FONT><FONT color=3D#cdcd00>%users</FONT><FONT =
color=3D#bebebe>
</FONT><FONT color=3D#ff7f50>keys</FONT><FONT =
color=3D#00ffff>(</FONT><FONT color=3D#cdcd00>%users</FONT><FONT =
color=3D#00ffff>)</FONT> =3D <FONT color=3D#cdcd00>512</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ff7f50>keys</FONT><FONT =
color=3D#00ffff>(</FONT><FONT color=3D#cdcd00>%users</FONT><FONT =
color=3D#00ffff>)</FONT> =3D <FONT color=3D#cdcd00>1000</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN274>Finding the Most Common =
Anything</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#cdcd00>%count</FONT> =3D <FONT =
color=3D#00ffff>();</FONT>
<FONT color=3D#ffa500>foreach</FONT> <FONT =
color=3D#9ac0cd>$element</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@ARRAY</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#cdcd00>$count</FONT><FONT =
color=3D#00ffff>{</FONT>$element<FONT color=3D#00ffff>}</FONT>++<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN277>Representing Relationships Between =
Data</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#cdcd00>%father</FONT> =3D <FONT =
color=3D#00ffff>(</FONT> <FONT color=3D#00cd00>'Cain'</FONT>      =
=3D&gt; <FONT color=3D#00cd00>'Adam'</FONT>,
            <FONT color=3D#00cd00>'Abel'</FONT>      =3D&gt; <FONT =
color=3D#00cd00>'Adam'</FONT>,
            <FONT color=3D#00cd00>'Seth'</FONT>      =3D&gt; <FONT =
color=3D#00cd00>'Adam'</FONT>,
            <FONT color=3D#00cd00>'Enoch'</FONT>     =3D&gt; <FONT =
color=3D#00cd00>'Cain'</FONT>,
            <FONT color=3D#00cd00>'Irad'</FONT>      =3D&gt; <FONT =
color=3D#00cd00>'Enoch'</FONT>,
            <FONT color=3D#00cd00>'Mehujael'</FONT>  =3D&gt; <FONT =
color=3D#00cd00>'Irad'</FONT>,
            <FONT color=3D#00cd00>'Methusael'</FONT> =3D&gt; <FONT =
color=3D#00cd00>'Mehujael'</FONT>,
            <FONT color=3D#00cd00>'Lamech'</FONT>    =3D&gt; <FONT =
color=3D#00cd00>'Methusael'</FONT>,
            <FONT color=3D#00cd00>'Jabal'</FONT>     =3D&gt; <FONT =
color=3D#00cd00>'Lamech'</FONT>,
            <FONT color=3D#00cd00>'Jubal'</FONT>     =3D&gt; <FONT =
color=3D#00cd00>'Lamech'</FONT>,
            <FONT color=3D#00cd00>'Tubalcain'</FONT> =3D&gt; <FONT =
color=3D#00cd00>'Lamech'</FONT>,
            <FONT color=3D#00cd00>'Enos'</FONT>      =3D&gt; <FONT =
color=3D#00cd00>'Seth'</FONT> <FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT>&lt;&gt;<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>chomp</FONT><FONT color=3D#00ffff>;</FONT>
    <FONT color=3D#ffa500>do</FONT> <FONT color=3D#00ffff>{</FONT>
        <FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"$_ =
"</FONT><FONT color=3D#00ffff>;</FONT>        <FONT color=3D#bebebe># =
print the current name
</FONT>        $_ =3D <FONT color=3D#cdcd00>$father</FONT><FONT =
color=3D#00ffff>{</FONT>$_<FONT color=3D#00ffff>};</FONT>   <FONT =
color=3D#bebebe># set $_ to $_'s father
</FONT>    <FONT color=3D#00ffff>}</FONT> <FONT =
color=3D#ffa500>while</FONT> <FONT color=3D#ff7f50>defined</FONT><FONT =
color=3D#00ffff>;</FONT>        <FONT color=3D#bebebe># until we run out =
of fathers
</FONT>    <FONT color=3D#ff7f50>print</FONT> <FONT =
color=3D#00cd00>"\n"</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>while</FONT> <FONT color=3D#00ffff>(</FONT> =
<FONT color=3D#00ffff>(</FONT>$k,$v<FONT color=3D#00ffff>)</FONT> =3D =
<FONT color=3D#ff7f50>each</FONT> <FONT color=3D#cdcd00>%father</FONT> =
<FONT color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>push</FONT><FONT color=3D#00ffff>(</FONT> =
@<FONT color=3D#00ffff>{</FONT> <FONT =
color=3D#cdcd00>$children</FONT><FONT color=3D#00ffff>{</FONT>$v<FONT =
color=3D#00ffff>}</FONT> <FONT color=3D#00ffff>}</FONT>, $k <FONT =
color=3D#00ffff>);</FONT>
<FONT color=3D#00ffff>}</FONT>

$" =3D <FONT color=3D#00cd00>', '</FONT><FONT color=3D#00ffff>;</FONT>   =
               <FONT color=3D#bebebe># separate output with commas
</FONT><FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT>&lt;&gt;<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>chomp</FONT><FONT color=3D#00ffff>;</FONT>
    <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdcd00>$children</FONT><FONT color=3D#00ffff>{</FONT>$_<FONT =
color=3D#00ffff>})</FONT> <FONT color=3D#00ffff>{</FONT>
        <FONT color=3D#cdad00>@children</FONT> =3D @<FONT =
color=3D#00ffff>{</FONT><FONT color=3D#cdcd00>$children</FONT><FONT =
color=3D#00ffff>{</FONT>$_<FONT color=3D#00ffff>}};</FONT>
    <FONT color=3D#00ffff>}</FONT> <FONT color=3D#ffa500>else</FONT> =
<FONT color=3D#00ffff>{</FONT>
        <FONT color=3D#cdad00>@children</FONT> =3D <FONT =
color=3D#00cd00>"nobody"</FONT><FONT color=3D#00ffff>;</FONT>
    <FONT color=3D#00ffff>}</FONT>
    <FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"$_ begat =
</FONT><FONT color=3D#cdad00>@children</FONT><FONT =
color=3D#00cd00>.\n"</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>foreach</FONT> <FONT =
color=3D#9ac0cd>$file</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@files</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa5
12345

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