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<h3 class="section" id="Escape-Sequences-in-String-Constants-1"><span>5.1 Escape Sequences in String Constants<a class="copiable-link" href="#Escape-Sequences-in-String-Constants-1"> ¶</a></span></h3>
<a class="index-entry-id" id="index-escape-sequence-notation"></a>
<p>In double-quoted strings, the backslash character is used to introduce
<em class="dfn">escape sequences</em> that represent other characters. For example,
‘<samp class="samp">\n</samp>’ embeds a newline character in a double-quoted string and
‘<samp class="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">
<div class="group"><pre class="example-preformatted">double ("\n")
⇒ 10
double ('\n')
⇒ [ 92 110 ]
</pre></div></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 class="table">
<dt><code class="code">\\</code></dt>
<dd><p>Represents a literal backslash, ‘<samp class="samp">\</samp>’.
</p>
</dd>
<dt><code class="code">\"</code></dt>
<dd><p>Represents a literal double-quote character, ‘<samp class="samp">"</samp>’.
</p>
</dd>
<dt><code class="code">\'</code></dt>
<dd><p>Represents a literal single-quote character, ‘<samp class="samp">'</samp>’.
</p>
</dd>
<dt><code class="code">\0</code></dt>
<dd><p>Represents the null character, control-@, ASCII code 0.
</p>
</dd>
<dt><code class="code">\a</code></dt>
<dd><p>Represents the “alert” character, control-g, ASCII code 7.
</p>
</dd>
<dt><code class="code">\b</code></dt>
<dd><p>Represents a backspace, control-h, ASCII code 8.
</p>
</dd>
<dt><code class="code">\f</code></dt>
<dd><p>Represents a formfeed, control-l, ASCII code 12.
</p>
</dd>
<dt><code class="code">\n</code></dt>
<dd><p>Represents a newline, control-j, ASCII code 10.
</p>
</dd>
<dt><code class="code">\r</code></dt>
<dd><p>Represents a carriage return, control-m, ASCII code 13.
</p>
</dd>
<dt><code class="code">\t</code></dt>
<dd><p>Represents a horizontal tab, control-i, ASCII code 9.
</p>
</dd>
<dt><code class="code">\v</code></dt>
<dd><p>Represents a vertical tab, control-k, ASCII code 11.
</p>
</dd>
<dt><code class="code">\<var class="var">nnn</var></code></dt>
<dd><p>Represents the octal value <var class="var">nnn</var>, where <var class="var">nnn</var> are one to three
digits between 0 and 7. For example, the code for the ASCII ESC
(escape) character is ‘<samp class="samp">\033</samp>’.
</p>
</dd>
<dt><code class="code">\x<var class="var">hh</var>…</code></dt>
<dd><p>Represents the hexadecimal value <var class="var">hh</var>, where <var class="var">hh</var> are hexadecimal
digits (‘<samp class="samp">0</samp>’ through ‘<samp class="samp">9</samp>’ and either ‘<samp class="samp">A</samp>’ through ‘<samp class="samp">F</samp>’ or
‘<samp class="samp">a</samp>’ through ‘<samp class="samp">f</samp>’). Like the same construct in <small class="sc">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">
<div class="group"><pre class="example-preformatted">'I can''t escape'
⇒ I can't escape
</pre></div></div>
<p>In scripts the two different string types can be distinguished if necessary
by using <code class="code">is_dq_string</code> and <code class="code">is_sq_string</code>.
</p>
<a class="anchor" id="XREFis_005fdq_005fstring"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-is_005fdq_005fstring"><span><code class="def-type"><var class="var">tf</var> =</code> <strong class="def-name">is_dq_string</strong> <code class="def-code-arguments">(<var class="var">x</var>)</code><a class="copiable-link" href="#index-is_005fdq_005fstring"> ¶</a></span></dt>
<dd><p>Return true if <var class="var">x</var> is a double-quoted character string.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFis_005fsq_005fstring">is_sq_string</a>, <a class="ref" href="Character-Arrays.html#XREFischar">ischar</a>.
</p></dd></dl>
<a class="anchor" id="XREFis_005fsq_005fstring"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-is_005fsq_005fstring"><span><code class="def-type"><var class="var">tf</var> =</code> <strong class="def-name">is_sq_string</strong> <code class="def-code-arguments">(<var class="var">x</var>)</code><a class="copiable-link" href="#index-is_005fsq_005fstring"> ¶</a></span></dt>
<dd><p>Return true if <var class="var">x</var> is a single-quoted character string.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFis_005fdq_005fstring">is_dq_string</a>, <a class="ref" href="Character-Arrays.html#XREFischar">ischar</a>.
</p></dd></dl>
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