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<a name="Escape-Sequences-in-String-Constants"></a>
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Next: <a href="Character-Arrays.html#Character-Arrays" accesskey="n" rel="next">Character Arrays</a>, Up: <a href="Strings.html#Strings" accesskey="u" rel="up">Strings</a> [<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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<a name="Escape-Sequences-in-String-Constants-1"></a>
<h3 class="section">5.1 Escape Sequences in String Constants</h3>
<a name="index-escape-sequence-notation"></a>
<p>In double-quoted strings, the backslash character is used to introduce
<em>escape sequences</em> that represent other characters. For example,
‘<samp>\n</samp>’ embeds a newline character in a double-quoted string and
‘<samp>\"</samp>’ embeds a double quote character. In single-quoted strings, backslash
is not a special character. Here is an example showing the difference:
</p>
<div class="example">
<pre class="example">double ("\n")
⇒ 10
double ('\n')
⇒ [ 92 110 ]
</pre></div>
<p>Here is a table of all the escape sequences used in Octave (within
double quoted strings). They are the same as those used in the C
programming language.
</p>
<dl compact="compact">
<dt><code>\\</code></dt>
<dd><p>Represents a literal backslash, ‘<samp>\</samp>’.
</p>
</dd>
<dt><code>\"</code></dt>
<dd><p>Represents a literal double-quote character, ‘<samp>"</samp>’.
</p>
</dd>
<dt><code>\'</code></dt>
<dd><p>Represents a literal single-quote character, ‘<samp>'</samp>’.
</p>
</dd>
<dt><code>\0</code></dt>
<dd><p>Represents the null character, control-@, ASCII code 0.
</p>
</dd>
<dt><code>\a</code></dt>
<dd><p>Represents the “alert” character, control-g, ASCII code 7.
</p>
</dd>
<dt><code>\b</code></dt>
<dd><p>Represents a backspace, control-h, ASCII code 8.
</p>
</dd>
<dt><code>\f</code></dt>
<dd><p>Represents a formfeed, control-l, ASCII code 12.
</p>
</dd>
<dt><code>\n</code></dt>
<dd><p>Represents a newline, control-j, ASCII code 10.
</p>
</dd>
<dt><code>\r</code></dt>
<dd><p>Represents a carriage return, control-m, ASCII code 13.
</p>
</dd>
<dt><code>\t</code></dt>
<dd><p>Represents a horizontal tab, control-i, ASCII code 9.
</p>
</dd>
<dt><code>\v</code></dt>
<dd><p>Represents a vertical tab, control-k, ASCII code 11.
</p>
</dd>
<dt><code>\<var>nnn</var></code></dt>
<dd><p>Represents the octal value <var>nnn</var>, where <var>nnn</var> are one to three
digits between 0 and 7. For example, the code for the ASCII ESC
(escape) character is ‘<samp>\033</samp>’.
</p>
</dd>
<dt><code>\x<var>hh</var>…</code></dt>
<dd><p>Represents the hexadecimal value <var>hh</var>, where <var>hh</var> are hexadecimal
digits (‘<samp>0</samp>’ through ‘<samp>9</samp>’ and either ‘<samp>A</samp>’ through ‘<samp>F</samp>’ or
‘<samp>a</samp>’ through ‘<samp>f</samp>’). Like the same construct in <small>ANSI</small> C,
the escape sequence continues until the first non-hexadecimal digit is seen.
However, using more than two hexadecimal digits produces undefined results.
</p></dd>
</dl>
<p>In a single-quoted string there is only one escape sequence: you may insert a
single quote character using two single quote characters in succession. For
example,
</p>
<div class="example">
<pre class="example">'I can''t escape'
⇒ I can't escape
</pre></div>
<p>In scripts the two different string types can be distinguished if necessary
by using <code>is_dq_string</code> and <code>is_sq_string</code>.
</p>
<a name="XREFis_005fdq_005fstring"></a><dl>
<dt><a name="index-is_005fdq_005fstring"></a><em></em> <strong>is_dq_string</strong> <em>(<var>x</var>)</em></dt>
<dd><p>Return true if <var>x</var> is a double-quoted character string.
</p>
<p><strong>See also:</strong> <a href="#XREFis_005fsq_005fstring">is_sq_string</a>, <a href="Character-Arrays.html#XREFischar">ischar</a>.
</p></dd></dl>
<a name="XREFis_005fsq_005fstring"></a><dl>
<dt><a name="index-is_005fsq_005fstring"></a><em></em> <strong>is_sq_string</strong> <em>(<var>x</var>)</em></dt>
<dd><p>Return true if <var>x</var> is a single-quoted character string.
</p>
<p><strong>See also:</strong> <a href="#XREFis_005fdq_005fstring">is_dq_string</a>, <a href="Character-Arrays.html#XREFischar">ischar</a>.
</p></dd></dl>
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Next: <a href="Character-Arrays.html#Character-Arrays" accesskey="n" rel="next">Character Arrays</a>, Up: <a href="Strings.html#Strings" accesskey="u" rel="up">Strings</a> [<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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