lass="keywordtype">string</span> = user_string(string_name, <span class="keywordtype">string</span>)</div><div class="line"><a name="l00033"></a><span class="lineno">   33</span>&#160;if ~ischar(string_name)</div><div class="line"><a name="l00034"></a><span class="lineno">   34</span>&#160;    error(&#39;string_name must be a <span class="keywordtype">string</span>.&#39;);</div><div class="line"><a name="l00035"></a><span class="lineno">   35</span>&#160;end</div><div class="line"><a name="l00036"></a><span