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<title>Debugging with GDB: Character Sets</title>

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<a name="Character-Sets"></a>
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</div>
<hr>
<a name="Character-Sets-1"></a>
<h3 class="section">10.20 Character Sets</h3>
<a name="index-character-sets"></a>
<a name="index-charset"></a>
<a name="index-translating-between-character-sets"></a>
<a name="index-host-character-set"></a>
<a name="index-target-character-set"></a>

<p>If the program you are debugging uses a different character set to
represent characters and strings than the one <small>GDB</small> uses itself,
<small>GDB</small> can automatically translate between the character sets for
you.  The character set <small>GDB</small> uses we call the <em>host
character set</em>; the one the inferior program uses we call the
<em>target character set</em>.
</p>
<p>For example, if you are running <small>GDB</small> on a <small>GNU</small>/Linux system, which
uses the ISO Latin 1 character set, but you are using <small>GDB</small>&rsquo;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 <small>EBCDIC</small> character set,
then the host character set is Latin-1, and the target character set is
<small>EBCDIC</small>.  If you give <small>GDB</small> the command <code>set
target-charset EBCDIC-US</code>, then <small>GDB</small> translates between
<small>EBCDIC</small> and Latin 1 as you print character or string values, or use
character and string literals in expressions.
</p>
<p><small>GDB</small> 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>
<p>Here are the commands for controlling <small>GDB</small>&rsquo;s character set
support:
</p>
<dl compact="compact">
<dt><code>set target-charset <var>charset</var></code></dt>
<dd><a name="index-set-target_002dcharset"></a>
<p>Set the current target character set to <var>charset</var>.  To display the
list of supported target character sets, type
<kbd>set&nbsp;<span class="nolinebreak">target-charset</span>&nbsp;<span class="key">TAB</span><span class="key">TAB</span><!-- /@w --></kbd>.
</p>
</dd>
<dt><code>set host-charset <var>charset</var></code></dt>
<dd><a name="index-set-host_002dcharset"></a>
<p>Set the current host character set to <var>charset</var>.
</p>
<p>By default, <small>GDB</small> 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, <small>GDB</small> cannot
automatically determine the appropriate host character set.  In this
case, <small>GDB</small> uses &lsquo;<samp>UTF-8</samp>&rsquo;.
</p>
<p><small>GDB</small> can only use certain character sets as its host character
set.  If you type <kbd>set&nbsp;<span class="nolinebreak">host-charset</span>&nbsp;<span class="key">TAB</span><span class="key">TAB</span><!-- /@w --></kbd>,
<small>GDB</small> will list the host character sets it supports.
</p>
</dd>
<dt><code>set charset <var>charset</var></code></dt>
<dd><a name="index-set-charset"></a>
<p>Set the current host and target character sets to <var>charset</var>.  As
above, if you type <kbd>set&nbsp;charset&nbsp;<span class="key">TAB</span><span class="key">TAB</span><!-- /@w --></kbd>,
<small>GDB</small> will list the names of the character sets that can be used
for both host and target.
</p>
</dd>
<dt><code>show charset</code></dt>
<dd><a name="index-show-charset"></a>
<p>Show the names of the current host and target character sets.
</p>
</dd>
<dt><code>show host-charset</code></dt>
<dd><a name="index-show-host_002dcharset"></a>
<p>Show the name of the current host character set.
</p>
</dd>
<dt><code>show target-charset</code></dt>
<dd><a name="index-show-target_002dcharset"></a>
<p>Show the name of the current target character set.
</p>
</dd>
<dt><code>set target-wide-charset <var>charset</var></code></dt>
<dd><a name="index-set-target_002dwide_002dcharset"></a>
<p>Set the current target&rsquo;s wide character set to <var>charset</var>.  This is
the character set used by the target&rsquo;s <code>wchar_t</code> type.  To
display the list of supported wide character sets, type
<kbd>set&nbsp;<span class="nolinebreak">target-wide-charset</span>&nbsp;<span class="key">TAB</span><span class="key">TAB</span><!-- /@w --></kbd>.
</p>
</dd>
<dt><code>show target-wide-charset</code></dt>
<dd><a name="index-show-target_002dwide_002dcharset"></a>
<p>Show the name of the current target&rsquo;s wide character set.
</p></dd>
</dl>

<p>Here is an example of <small>GDB</small>&rsquo;s character set support in action.
Assume that the following source code has been placed in the file
<samp>charset-test.c</samp>:
</p>
<div class="smallexample">
<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 (&quot;Hello, world!\n&quot;);
}
</pre></div>

<p>In this program, <code>ascii_hello</code> and <code>ibm1047_hello</code> are arrays
containing the string &lsquo;<samp>Hello, world!</samp>&rsquo; followed by a newline,
encoded in the <small>ASCII</small> and <small>IBM1047</small> character sets.
</p>
<p>We compile the program, and invoke the debugger on it:
</p>
<div class="smallexample">
<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.
&hellip;
(gdb)
</pre></div>

<p>We can use the <code>show charset</code> command to see what character sets
<small>GDB</small> is currently using to interpret and display characters and
strings:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) show charset
The current host and target character set is `ISO-8859-1'.
(gdb)
</pre></div>

<p>For the sake of printing this manual, let&rsquo;s use <small>ASCII</small> as our
initial character set:
</p><div class="smallexample">
<pre class="smallexample">(gdb) set charset ASCII
(gdb) show charset
The current host and target character set is `ASCII'.
(gdb)
</pre></div>

<p>Let&rsquo;s assume that <small>ASCII</small> is indeed the correct character set for our
host system &mdash; in other words, let&rsquo;s assume that if <small>GDB</small> prints
characters using the <small>ASCII</small> character set, our terminal will display
them properly.  Since our current target character set is also
<small>ASCII</small>, the contents of <code>ascii_hello</code> print legibly:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) print ascii_hello
$1 = 0x401698 &quot;Hello, world!\n&quot;
(gdb) print ascii_hello[0]
$2 = 72 'H'
(gdb)
</pre></div>

<p><small>GDB</small> uses the target character set for character and string
literals you use in expressions:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) print '+'
$3 = 43 '+'
(gdb)
</pre></div>

<p>The <small>ASCII</small> character set uses the number 43 to encode the &lsquo;<samp>+</samp>&rsquo;
character.
</p>
<p><small>GDB</small> 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 <small>ASCII</small>, we get jibberish:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) print ibm1047_hello
$4 = 0x4016a8 &quot;\310\205\223\223\226k@\246\226\231\223\204Z%&quot;
(gdb) print ibm1047_hello[0]
$5 = 200 '\310'
(gdb)
</pre></div>

<p>If we invoke the <code>set target-charset</code> followed by <tt class="key">TAB</tt><tt class="key">TAB</tt>,
<small>GDB</small> tells us the character sets it supports:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) set target-charset
ASCII       EBCDIC-US   IBM1047     ISO-8859-1
(gdb) set target-charset
</pre></div>

<p>We can select <small>IBM1047</small> as our target character set, and examine the
program&rsquo;s strings again.  Now the <small>ASCII</small> string is wrong, but
<small>GDB</small> translates the contents of <code>ibm1047_hello</code> from the
target character set, <small>IBM1047</small>, to the host character set,
<small>ASCII</small>, and they display correctly:
</p>
<div class="smallexample">
<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 &quot;\110\145%%?\054\040\167?\162%\144\041\012&quot;
(gdb) print ascii_hello[0]
$7 = 72 '\110'
(gdb) print ibm1047_hello
$8 = 0x4016a8 &quot;Hello, world!\n&quot;
(gdb) print ibm1047_hello[0]
$9 = 200 'H'
(gdb)
</pre></div>

<p>As above, <small>GDB</small> uses the target character set for character and
string literals you use in expressions:
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) print '+'
$10 = 78 '+'
(gdb)
</pre></div>

<p>The <small>IBM1047</small> character set uses the number 78 to encode the &lsquo;<samp>+</samp>&rsquo;
character.
</p>
<hr>
<div class="header">
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Next: <a href="Caching-Target-Data.html#Caching-Target-Data" accesskey="n" rel="next">Caching Target Data</a>, Previous: <a href="Core-File-Generation.html#Core-File-Generation" accesskey="p" rel="previous">Core File Generation</a>, Up: <a href="Data.html#Data" accesskey="u" rel="up">Data</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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