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<h3 class="section">10.20 Character Sets</h3>

<p><a name="index-character-sets-803"></a><a name="index-charset-804"></a><a name="index-translating-between-character-sets-805"></a><a name="index-host-character-set-806"></a><a name="index-target-character-set-807"></a>
If the program you are debugging uses a different character set to
represent characters and strings than the one <span class="sc">gdb</span> uses itself,
<span class="sc">gdb</span> can automatically translate between the character sets for
you.  The character set <span class="sc">gdb</span> uses we call the <dfn>host
character set</dfn>; the one the inferior program uses we call the
<dfn>target character set</dfn>.

   <p>For example, if you are running <span class="sc">gdb</span> on a <span class="sc">gnu</span>/Linux system, which
uses the ISO Latin 1 character set, but you are using <span class="sc">gdb</span>'s
remote protocol (see <a href="Remote-Debugging.html#Remote-Debugging">Remote Debugging</a>) to debug a program
running on an IBM mainframe, which uses the <span class="sc">ebcdic</span> character set,
then the host character set is Latin-1, and the target character set is
<span class="sc">ebcdic</span>.  If you give <span class="sc">gdb</span> the command <code>set
target-charset EBCDIC-US</code>, then <span class="sc">gdb</span> translates between
<span class="sc">ebcdic</span> and Latin 1 as you print character or string values, or use
character and string literals in expressions.

   <p><span class="sc">gdb</span> has no way to automatically recognize which character set
the inferior program uses; you must tell it, using the <code>set
target-charset</code> command, described below.

   <p>Here are the commands for controlling <span class="sc">gdb</span>'s character set
support:

     <dl>
<dt><code>set target-charset </code><var>charset</var><dd><a name="index-set-target_002dcharset-808"></a>Set the current target character set to <var>charset</var>.  To display the
list of supported target character sets, type
<kbd>set&nbsp;target-charset&nbsp;&lt;TAB&gt;&lt;TAB&gt;<!-- /@w --></kbd>.

     <br><dt><code>set host-charset </code><var>charset</var><dd><a name="index-set-host_002dcharset-809"></a>Set the current host character set to <var>charset</var>.

     <p>By default, <span class="sc">gdb</span> uses a host character set appropriate to the
system it is running on; you can override that default using the
<code>set host-charset</code> command.  On some systems, <span class="sc">gdb</span> cannot
automatically determine the appropriate host character set.  In this
case, <span class="sc">gdb</span> uses &lsquo;<samp><span class="samp">UTF-8</span></samp>&rsquo;.

     <p><span class="sc">gdb</span> can only use certain character sets as its host character
set.  If you type <kbd>set&nbsp;host-charset&nbsp;&lt;TAB&gt;&lt;TAB&gt;<!-- /@w --></kbd>,
<span class="sc">gdb</span> will list the host character sets it supports.

     <br><dt><code>set charset </code><var>charset</var><dd><a name="index-set-charset-810"></a>Set the current host and target character sets to <var>charset</var>.  As
above, if you type <kbd>set&nbsp;charset&nbsp;&lt;TAB&gt;&lt;TAB&gt;<!-- /@w --></kbd>,
<span class="sc">gdb</span> will list the names of the character sets that can be used
for both host and target.

     <br><dt><code>show charset</code><dd><a name="index-show-charset-811"></a>Show the names of the current host and target character sets.

     <br><dt><code>show host-charset</code><dd><a name="index-show-host_002dcharset-812"></a>Show the name of the current host character set.

     <br><dt><code>show target-charset</code><dd><a name="index-show-target_002dcharset-813"></a>Show the name of the current target character set.

     <br><dt><code>set target-wide-charset </code><var>charset</var><dd><a name="index-set-target_002dwide_002dcharset-814"></a>Set the current target's wide character set to <var>charset</var>.  This is
the character set used by the target's <code>wchar_t</code> type.  To
display the list of supported wide character sets, type
<kbd>set&nbsp;target-wide-charset&nbsp;&lt;TAB&gt;&lt;TAB&gt;<!-- /@w --></kbd>.

     <br><dt><code>show target-wide-charset</code><dd><a name="index-show-target_002dwide_002dcharset-815"></a>Show the name of the current target's wide character set. 
</dl>

   <p>Here is an example of <span class="sc">gdb</span>'s character set support in action. 
Assume that the following source code has been placed in the file
<samp><span class="file">charset-test.c</span></samp>:

<pre class="smallexample">     #include &lt;stdio.h&gt;
     
     char ascii_hello[]
       = {72, 101, 108, 108, 111, 44, 32, 119,
          111, 114, 108, 100, 33, 10, 0};
     char ibm1047_hello[]
       = {200, 133, 147, 147, 150, 107, 64, 166,
          150, 153, 147, 132, 90, 37, 0};
     
     main ()
     {
       printf ("Hello, world!\n");
     }
</pre>
   <p>In this program, <code>ascii_hello</code> and <code>ibm1047_hello</code> are arrays
containing the string &lsquo;<samp><span class="samp">Hello, world!</span></samp>&rsquo; followed by a newline,
encoded in the <span class="sc">ascii</span> and <span class="sc">ibm1047</span> character sets.

   <p>We compile the program, and invoke the debugger on it:

<pre class="smallexample">     $ gcc -g charset-test.c -o charset-test
     $ gdb -nw charset-test
     GNU gdb 2001-12-19-cvs
     Copyright 2001 Free Software Foundation, Inc.
     ...
     (gdb)
</pre>
   <p>We can use the <code>show charset</code> command to see what character sets
<span class="sc">gdb</span> is currently using to interpret and display characters and
strings:

<pre class="smallexample">     (gdb) show charset
     The current host and target character set is `ISO-8859-1'.
     (gdb)
</pre>
   <p>For the sake of printing this manual, let's use <span class="sc">ascii</span> as our
initial character set:
<pre class="smallexample">     (gdb) set charset ASCII
     (gdb) show charset
     The current host and target character set is `ASCII'.
     (gdb)
</pre>
   <p>Let's assume that <span class="sc">ascii</span> is indeed the correct character set for our
host system &mdash; in other words, let's assume that if <span class="sc">gdb</span> prints
characters using the <span class="sc">ascii</span> character set, our terminal will display
them properly.  Since our current target character set is also
<span class="sc">ascii</span>, the contents of <code>ascii_hello</code> print legibly:

<pre class="smallexample">     (gdb) print ascii_hello
     $1 = 0x401698 "Hello, world!\n"
     (gdb) print ascii_hello[0]
     $2 = 72 'H'
     (gdb)
</pre>
   <p><span class="sc">gdb</span> uses the target character set for character and string
literals you use in expressions:

<pre class="smallexample">     (gdb) print '+'
     $3 = 43 '+'
     (gdb)
</pre>
   <p>The <span class="sc">ascii</span> character set uses the number 43 to encode the &lsquo;<samp><span class="samp">+</span></samp>&rsquo;
character.

   <p><span class="sc">gdb</span> relies on the user to tell it which character set the
target program uses.  If we print <code>ibm1047_hello</code> while our target
character set is still <span class="sc">ascii</span>, we get jibberish:

<pre class="smallexample">     (gdb) print ibm1047_hello
     $4 = 0x4016a8 "\310\205\223\223\226k@\246\226\231\223\204Z%"
     (gdb) print ibm1047_hello[0]
     $5 = 200 '\310'
     (gdb)
</pre>
   <p>If we invoke the <code>set target-charset</code> followed by &lt;TAB&gt;&lt;TAB&gt;,
<span class="sc">gdb</span> tells us the character sets it supports:

<pre class="smallexample">     (gdb) set target-charset
     ASCII       EBCDIC-US   IBM1047     ISO-8859-1
     (gdb) set target-charset
</pre>
   <p>We can select <span class="sc">ibm1047</span> as our target character set, and examine the
program's strings again.  Now the <span class="sc">ascii</span> string is wrong, but
<span class="sc">gdb</span> translates the contents of <code>ibm1047_hello</code> from the
target character set, <span class="sc">ibm1047</span>, to the host character set,
<span class="sc">ascii</span>, and they display correctly:

<pre class="smallexample">     (gdb) set target-charset IBM1047
     (gdb) show charset
     The current host character set is `ASCII'.
     The current target character set is `IBM1047'.
     (gdb) print ascii_hello
     $6 = 0x401698 "\110\145%%?\054\040\167?\162%\144\041\012"
     (gdb) print ascii_hello[0]
     $7 = 72 '\110'
     (gdb) print ibm1047_hello
     $8 = 0x4016a8 "Hello, world!\n"
     (gdb) print ibm1047_hello[0]
     $9 = 200 'H'
     (gdb)
</pre>
   <p>As above, <span class="sc">gdb</span> uses the target character set for character and
string literals you use in expressions:

<pre class="smallexample">     (gdb) print '+'
     $10 = 78 '+'
     (gdb)
</pre>
   <p>The <span class="sc">ibm1047</span> character set uses the number 78 to encode the &lsquo;<samp><span class="samp">+</span></samp>&rsquo;
character.

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