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<h3 class="section">5.4 Comparing Strings</h3>
<p>Since a string is a character array, comparisons between strings work
element by element as the following example shows:
<pre class="example"> GNU = "GNU's Not UNIX";
spaces = (GNU == " ")
⇒ spaces =
0 0 0 0 0 1 0 0 0 1 0 0 0 0
</pre>
<p class="noindent">To determine if two strings are identical it is necessary to use the
<code>strcmp</code> function. It compares complete strings and is case
sensitive. <code>strncmp</code> compares only the first <code>N</code> characters (with
<code>N</code> given as a parameter). <code>strcmpi</code> and <code>strncmpi</code> are the
corresponding functions for case-insensitive comparison.
<!-- strfns.cc -->
<p><a name="doc_002dstrcmp"></a>
<div class="defun">
— Built-in Function: <b>strcmp</b> (<var>s1, s2</var>)<var><a name="index-strcmp-304"></a></var><br>
<blockquote><p>Return 1 if the character strings <var>s1</var> and <var>s2</var> are the same,
and 0 otherwise.
<p>If either <var>s1</var> or <var>s2</var> is a cell array of strings, then an array
of the same size is returned, containing the values described above for
every member of the cell array. The other argument may also be a cell
array of strings (of the same size or with only one element), char matrix
or character string.
<p><strong>Caution:</strong> For compatibility with <span class="sc">matlab</span>, Octave's strcmp
function returns 1 if the character strings are equal, and 0 otherwise.
This is just the opposite of the corresponding C library function.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dstrcmpi.html#doc_002dstrcmpi">strcmpi</a>, <a href="doc_002dstrncmp.html#doc_002dstrncmp">strncmp</a>, <a href="doc_002dstrncmpi.html#doc_002dstrncmpi">strncmpi</a>.
</p></blockquote></div>
<!-- strfns.cc -->
<p><a name="doc_002dstrncmp"></a>
<div class="defun">
— Built-in Function: <b>strncmp</b> (<var>s1, s2, n</var>)<var><a name="index-strncmp-305"></a></var><br>
<blockquote><p>Return 1 if the first <var>n</var> characters of strings <var>s1</var> and <var>s2</var> are the same,
and 0 otherwise.
<pre class="example"> strncmp ("abce", "abcd", 3)
⇒ 1
</pre>
<p>If either <var>s1</var> or <var>s2</var> is a cell array of strings, then an array
of the same size is returned, containing the values described above for
every member of the cell array. The other argument may also be a cell
array of strings (of the same size or with only one element), char matrix
or character string.
<pre class="example"> strncmp ("abce", {"abcd", "bca", "abc"}, 3)
⇒ [1, 0, 1]
</pre>
<p><strong>Caution:</strong> For compatibility with <span class="sc">matlab</span>, Octave's strncmp
function returns 1 if the character strings are equal, and 0 otherwise.
This is just the opposite of the corresponding C library function.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dstrncmpi.html#doc_002dstrncmpi">strncmpi</a>, <a href="doc_002dstrcmp.html#doc_002dstrcmp">strcmp</a>, <a href="doc_002dstrcmpi.html#doc_002dstrcmpi">strcmpi</a>.
</p></blockquote></div>
<!-- ./strings/strcmpi.m -->
<p><a name="doc_002dstrcmpi"></a>
<div class="defun">
— Function File: <b>strcmpi</b> (<var>s1, s2</var>)<var><a name="index-strcmpi-306"></a></var><br>
<blockquote><p>Ignoring case, return 1 if the character strings (or character
arrays) <var>s1</var> and <var>s2</var> are the same, and 0 otherwise.
<p>If either <var>s1</var> or <var>s2</var> is a cell array of strings, then an array
of the same size is returned, containing the values described above for
every member of the cell array. The other argument may also be a cell
array of strings (of the same size or with only one element), char matrix
or character string.
<p><strong>Caution:</strong> For compatibility with <span class="sc">matlab</span>, Octave's strcmpi
function returns 1 if the character strings are equal, and 0 otherwise.
This is just the opposite of the corresponding C library function.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dstrcmp.html#doc_002dstrcmp">strcmp</a>, <a href="doc_002dstrncmp.html#doc_002dstrncmp">strncmp</a>, <a href="doc_002dstrncmpi.html#doc_002dstrncmpi">strncmpi</a>.
</p></blockquote></div>
<!-- ./strings/strncmpi.m -->
<p><a name="doc_002dstrncmpi"></a>
<div class="defun">
— Function File: <b>strncmpi</b> (<var>s1, s2, n</var>)<var><a name="index-strncmpi-307"></a></var><br>
<blockquote><p>Ignoring case, return 1 if the first <var>n</var> characters of character
strings (or character arrays) <var>s1</var> and <var>s2</var> are the same, and
0 otherwise.
<p>If either <var>s1</var> or <var>s2</var> is a cell array of strings, then an array
of the same size is returned, containing the values described above for
every member of the cell array. The other argument may also be a cell
array of strings (of the same size or with only one element), char matrix
or character string.
<p><strong>Caution:</strong> For compatibility with <span class="sc">matlab</span>, Octave's strncmpi
function returns 1 if the character strings are equal, and 0 otherwise.
This is just the opposite of the corresponding C library function.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dstrcmp.html#doc_002dstrcmp">strcmp</a>, <a href="doc_002dstrcmpi.html#doc_002dstrcmpi">strcmpi</a>, <a href="doc_002dstrncmp.html#doc_002dstrncmp">strncmp</a>.
</p></blockquote></div>
<!-- ./strings/validatestring.m -->
<p><a name="doc_002dvalidatestring"></a>
<div class="defun">
— Function File: <var>validstr</var> = <b>validatestring</b> (<var>str, strarray</var>)<var><a name="index-validatestring-308"></a></var><br>
— Function File: <var>validstr</var> = <b>validatestring</b> (<var>str, strarray, funcname</var>)<var><a name="index-validatestring-309"></a></var><br>
— Function File: <var>validstr</var> = <b>validatestring</b> (<var>str, strarray, funcname, varname</var>)<var><a name="index-validatestring-310"></a></var><br>
— Function File: <var>validstr</var> = <b>validatestring</b> (<var><small class="dots">...</small>, position</var>)<var><a name="index-validatestring-311"></a></var><br>
<blockquote><p>Verify that <var>str</var> is a string or substring of an element of
<var>strarray</var>.
<p><var>str</var> is a character string to be tested, and <var>strarray</var> is a
cellstr of valid values. <var>validstr</var> will be the validated form
of <var>str</var> where validation is defined as <var>str</var> being a member
or substring of <var>validstr</var>. If <var>str</var> is a substring of
<var>validstr</var> and there are multiple matches, the shortest match
will be returned if all matches are substrings of each other, and an
error will be raised if the matches are not substrings of each other.
<p>All comparisons are case insensitive.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dstrcmp.html#doc_002dstrcmp">strcmp</a>, <a href="doc_002dstrcmpi.html#doc_002dstrcmpi">strcmpi</a>.
</p></blockquote></div>
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