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Previous: <a rel="previous" accesskey="p" href="Creating-Strings.html#Creating-Strings">Creating Strings</a>,
Up: <a rel="up" accesskey="u" href="Strings.html#Strings">Strings</a>
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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.
<!-- strcmp src/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-349"></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>
<!-- strncmp src/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-350"></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>
<!-- strcmpi src/strfns.cc -->
<p><a name="doc_002dstrcmpi"></a>
<div class="defun">
— Built-in Function: <b>strcmpi</b> (<var>s1, s2</var>)<var><a name="index-strcmpi-351"></a></var><br>
<blockquote><p>Return 1 if the character strings <var>s1</var> and <var>s2</var> are the same,
disregarding case of alphabetic characters, 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.
<p><strong>Caution:</strong> National alphabets are not supported.
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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>
<!-- strncmpi src/strfns.cc -->
<p><a name="doc_002dstrncmpi"></a>
<div class="defun">
— Built-in Function: <b>strncmpi</b> (<var>s1, s2, n</var>)<var><a name="index-strncmpi-352"></a></var><br>
<blockquote><p>Return 1 if the first <var>n</var> character of <var>s1</var> and <var>s2</var> are the
same, disregarding case of alphabetic characters, 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.
<p><strong>Caution:</strong> National alphabets are not supported.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dstrncmp.html#doc_002dstrncmp">strncmp</a>, <a href="doc_002dstrcmp.html#doc_002dstrcmp">strcmp</a>, <a href="doc_002dstrcmpi.html#doc_002dstrcmpi">strcmpi</a>.
</p></blockquote></div>
<!-- validatestring scripts/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-353"></a></var><br>
— Function File: <var>validstr</var> = <b>validatestring</b> (<var>str, strarray, funcname</var>)<var><a name="index-validatestring-354"></a></var><br>
— Function File: <var>validstr</var> = <b>validatestring</b> (<var>str, strarray, funcname, varname</var>)<var><a name="index-validatestring-355"></a></var><br>
— Function File: <var>validstr</var> = <b>validatestring</b> (<var><small class="dots">...</small>, position</var>)<var><a name="index-validatestring-356"></a></var><br>
<blockquote><p>Verify that <var>str</var> is an element, or substring of an element, in
<var>strarray</var>.
<p>When <var>str</var> is a character string to be tested, and <var>strarray</var> is a
cellstr of valid values, then <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>. This is useful for both verifying
and expanding short options, such as "r", to their longer forms, such as
"red". 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. Otherwise, an error will be raised because the
expansion of <var>str</var> is ambiguous. All comparisons are case insensitive.
<p>The additional inputs <var>funcname</var>, <var>varname</var>, and <var>position</var>
are optional and will make any generated validation error message more
specific.
<p>Examples:
<!-- Set example in small font to prevent overfull line -->
<pre class="smallexample"> validatestring ("r", {"red", "green", "blue"})
⇒ "red"
validatestring ("b", {"red", "green", "blue", "black"})
⇒ error: validatestring: multiple unique matches were found for 'b':
blue, black
</pre>
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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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