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Next: <a href="Concatenating-Strings.html" accesskey="n" rel="next">Concatenating Strings</a>, Up: <a href="String-Operations.html" accesskey="u" rel="up">String Operations</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<h4 class="subsection" id="Common-String-Operations-1"><span>5.3.1 Common String Operations<a class="copiable-link" href="#Common-String-Operations-1"> ¶</a></span></h4>
<p>The following functions are useful to perform common String operations.
</p>
<a class="anchor" id="XREFlower"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-lower"><span><code class="def-type"><var class="var">y</var> =</code> <strong class="def-name">lower</strong> <code class="def-code-arguments">(<var class="var">s</var>)</code><a class="copiable-link" href="#index-lower"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-tolower"><span><code class="def-type"><var class="var">y</var> =</code> <strong class="def-name">tolower</strong> <code class="def-code-arguments">(<var class="var">s</var>)</code><a class="copiable-link" href="#index-tolower"> ¶</a></span></dt>
<dd><p>Return a copy of the string or cell string <var class="var">s</var>, with each uppercase
character replaced by the corresponding lowercase one; non-alphabetic
characters are left unchanged.
</p>
<p>For example:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">lower ("MiXeD cAsE 123")
⇒ "mixed case 123"
</pre></div></div>
<p>Programming Note: <code class="code">tolower</code> is an alias for <code class="code">lower</code> and either name
can be used in Octave.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFupper">upper</a>.
</p></dd></dl>
<a class="anchor" id="XREFupper"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-upper"><span><code class="def-type"><var class="var">y</var> =</code> <strong class="def-name">upper</strong> <code class="def-code-arguments">(<var class="var">s</var>)</code><a class="copiable-link" href="#index-upper"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-toupper"><span><code class="def-type"><var class="var">y</var> =</code> <strong class="def-name">toupper</strong> <code class="def-code-arguments">(<var class="var">s</var>)</code><a class="copiable-link" href="#index-toupper"> ¶</a></span></dt>
<dd><p>Return a copy of the string or cell string <var class="var">s</var>, with each lowercase
character replaced by the corresponding uppercase one; non-alphabetic
characters are left unchanged.
</p>
<p>For example:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">upper ("MiXeD cAsE 123")
⇒ "MIXED CASE 123"
</pre></div></div>
<p>Programming Note: <code class="code">toupper</code> is an alias for <code class="code">upper</code> and either name
can be used in Octave.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFlower">lower</a>.
</p></dd></dl>
<a class="anchor" id="XREFdeblank"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-deblank"><span><code class="def-type"><var class="var">s</var> =</code> <strong class="def-name">deblank</strong> <code class="def-code-arguments">(<var class="var">s</var>)</code><a class="copiable-link" href="#index-deblank"> ¶</a></span></dt>
<dd><p>Remove trailing whitespace and nulls from <var class="var">s</var>.
</p>
<p>If <var class="var">s</var> is a matrix, <var class="var">deblank</var> trims each row to the length of
the longest string. If <var class="var">s</var> is a cell array of strings, operate
recursively on each string element.
</p>
<p>Examples:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">deblank (" abc ")
⇒ " abc"
deblank ([" abc "; " def "])
⇒ [" abc " ; " def"]
</pre></div></div>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFstrtrim">strtrim</a>.
</p></dd></dl>
<a class="anchor" id="XREFstrtrim"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-strtrim"><span><code class="def-type"><var class="var">s</var> =</code> <strong class="def-name">strtrim</strong> <code class="def-code-arguments">(<var class="var">s</var>)</code><a class="copiable-link" href="#index-strtrim"> ¶</a></span></dt>
<dd><p>Remove leading and trailing whitespace from <var class="var">s</var>.
</p>
<p>If <var class="var">s</var> is a matrix, <var class="var">strtrim</var> trims each row to the length of
longest string. If <var class="var">s</var> is a cell array of strings, operate recursively
on each string element.
</p>
<p>For example:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">strtrim (" abc ")
⇒ "abc"
strtrim ([" abc "; " def "])
⇒ ["abc " ; " def"]
</pre></div></div>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFdeblank">deblank</a>.
</p></dd></dl>
<a class="anchor" id="XREFstrtrunc"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-strtrunc"><span><code class="def-type"><var class="var">s</var> =</code> <strong class="def-name">strtrunc</strong> <code class="def-code-arguments">(<var class="var">s</var>, <var class="var">n</var>)</code><a class="copiable-link" href="#index-strtrunc"> ¶</a></span></dt>
<dd><p>Truncate the character string <var class="var">s</var> to length <var class="var">n</var>.
</p>
<p>If <var class="var">s</var> is a character matrix, then the number of columns is adjusted.
</p>
<p>If <var class="var">s</var> is a cell array of strings, then the operation is performed
on each cell element and the new cell array is returned.
</p></dd></dl>
<a class="anchor" id="XREFuntabify"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-untabify"><span><code class="def-type"><var class="var">str</var> =</code> <strong class="def-name">untabify</strong> <code class="def-code-arguments">(<var class="var">t</var>)</code><a class="copiable-link" href="#index-untabify"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-untabify-1"><span><code class="def-type"><var class="var">str</var> =</code> <strong class="def-name">untabify</strong> <code class="def-code-arguments">(<var class="var">t</var>, <var class="var">tw</var>)</code><a class="copiable-link" href="#index-untabify-1"> ¶</a></span></dt>
<dt class="deftypefnx def-cmd-deftypefn" id="index-untabify-2"><span><code class="def-type"><var class="var">str</var> =</code> <strong class="def-name">untabify</strong> <code class="def-code-arguments">(<var class="var">t</var>, <var class="var">tw</var>, <var class="var">deblank</var>)</code><a class="copiable-link" href="#index-untabify-2"> ¶</a></span></dt>
<dd><p>Replace TAB characters in <var class="var">t</var> with spaces.
</p>
<p>The input, <var class="var">t</var>, may be either a 2-D character array, or a cell array of
character strings. The output is the same class as the input.
</p>
<p>The tab width is specified by <var class="var">tw</var>, and defaults to eight.
</p>
<p>If the optional argument <var class="var">deblank</var> is true, then the spaces will be
removed from the end of the character data.
</p>
<p>The following example reads a file and writes an untabified version of the
same file with trailing spaces stripped.
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">fid = fopen ("tabbed_script.m");
text = char (fread (fid, "uchar")');
fclose (fid);
fid = fopen ("untabified_script.m", "w");
text = untabify (strsplit (text, "\n"), 8, true);
fprintf (fid, "%s\n", text{:});
fclose (fid);
</pre></div></div>
<p><strong class="strong">See also:</strong> <a class="ref" href="Character-Arrays.html#XREFstrjust">strjust</a>, <a class="ref" href="Splitting-and-Joining-Strings.html#XREFstrsplit">strsplit</a>, <a class="ref" href="#XREFdeblank">deblank</a>.
</p></dd></dl>
<a class="anchor" id="XREFdo_005fstring_005fescapes"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-do_005fstring_005fescapes"><span><code class="def-type"><var class="var">newstr</var> =</code> <strong class="def-name">do_string_escapes</strong> <code class="def-code-arguments">(<var class="var">string</var>)</code><a class="copiable-link" href="#index-do_005fstring_005fescapes"> ¶</a></span></dt>
<dd><p>Convert escape sequences in <var class="var">string</var> to the characters they represent.
</p>
<p>Escape sequences begin with a leading backslash
(<code class="code">'\'</code>) followed by 1–3 characters
(.e.g., <code class="code">"\n"</code> => newline).
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFundo_005fstring_005fescapes">undo_string_escapes</a>.
</p></dd></dl>
<a class="anchor" id="XREFundo_005fstring_005fescapes"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-undo_005fstring_005fescapes"><span><code class="def-type"><var class="var">newstr</var> =</code> <strong class="def-name">undo_string_escapes</strong> <code class="def-code-arguments">(<var class="var">string</var>)</code><a class="copiable-link" href="#index-undo_005fstring_005fescapes"> ¶</a></span></dt>
<dd><p>Convert special characters in <var class="var">string</var> back to their escaped forms.
</p>
<p>For example, the expression
</p>
<div class="example">
<pre class="example-preformatted"><var class="var">bell</var> = "\a";
</pre></div>
<p>assigns the value of the alert character (control-g, ASCII code 7) to the
string variable <code class="code">bell</code>. If this string is printed, the system will
ring the terminal bell (if it is possible). This is normally the desired
outcome. However, sometimes it is useful to be able to print the original
representation of the string, with the special characters replaced by their
escape sequences. For example,
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">octave:13> undo_string_escapes (bell)
ans = \a
</pre></div></div>
<p>replaces the unprintable alert character with its printable representation.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="#XREFdo_005fstring_005fescapes">do_string_escapes</a>.
</p></dd></dl>
</div>
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