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<span id="Validating-the-number-of-Arguments"></span><div class="header">
<p>
Next: <a href="Validating-the-type-of-Arguments.html" accesskey="n" rel="next">Validating the type of Arguments</a>, Up: <a href="Validating-Arguments.html" accesskey="u" rel="up">Validating Arguments</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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<hr>
<span id="Validating-the-number-of-Arguments-1"></span><h4 class="subsection">11.9.1 Validating the number of Arguments</h4>
<p>In Octave the following idiom is seen frequently at the beginning of a
function definition:
</p>
<div class="example">
<pre class="example">if (nargin < min_#_inputs || nargin > max_#_inputs)
print_usage ();
endif
</pre></div>
<p>which stops the function execution and prints a message about the correct
way to call the function whenever the number of inputs is wrong.
</p>
<p>Similar error checking is provided by <code>narginchk</code> and
<code>nargoutchk</code>.
</p>
<span id="XREFnarginchk"></span><dl>
<dt id="index-narginchk">: <em></em> <strong>narginchk</strong> <em>(<var>minargs</var>, <var>maxargs</var>)</em></dt>
<dd><p>Check for correct number of input arguments.
</p>
<p>Generate an error message if the number of arguments in the calling function
is outside the range <var>minargs</var> and <var>maxargs</var>. Otherwise, do
nothing.
</p>
<p>Both <var>minargs</var> and <var>maxargs</var> must be scalar numeric values. Zero,
Inf, and negative values are all allowed, and <var>minargs</var> and
<var>maxargs</var> may be equal.
</p>
<p>Note that this function evaluates <code>nargin</code> on the caller.
</p>
<p><strong>See also:</strong> <a href="#XREFnargoutchk">nargoutchk</a>, <a href="Raising-Errors.html#XREFerror">error</a>, <a href="Multiple-Return-Values.html#XREFnargout">nargout</a>, <a href="Defining-Functions.html#XREFnargin">nargin</a>.
</p></dd></dl>
<span id="XREFnargoutchk"></span><dl>
<dt id="index-nargoutchk">: <em></em> <strong>nargoutchk</strong> <em>(<var>minargs</var>, <var>maxargs</var>)</em></dt>
<dt id="index-nargoutchk-1">: <em><var>msgstr</var> =</em> <strong>nargoutchk</strong> <em>(<var>minargs</var>, <var>maxargs</var>, <var>nargs</var>)</em></dt>
<dt id="index-nargoutchk-2">: <em><var>msgstr</var> =</em> <strong>nargoutchk</strong> <em>(<var>minargs</var>, <var>maxargs</var>, <var>nargs</var>, "string")</em></dt>
<dt id="index-nargoutchk-3">: <em><var>msgstruct</var> =</em> <strong>nargoutchk</strong> <em>(<var>minargs</var>, <var>maxargs</var>, <var>nargs</var>, "struct")</em></dt>
<dd><p>Check for correct number of output arguments.
</p>
<p>In the first form, return an error if the number of arguments is not between
<var>minargs</var> and <var>maxargs</var>. Otherwise, do nothing. Note that this
function evaluates the value of <code>nargout</code> on the caller so its value
must have not been tampered with.
</p>
<p>Both <var>minargs</var> and <var>maxargs</var> must be numeric scalars. Zero, Inf,
and negative are all valid, and they can have the same value.
</p>
<p>For backwards compatibility, the other forms return an appropriate error
message string (or structure) if the number of outputs requested is
invalid.
</p>
<p>This is useful for checking to that the number of output arguments supplied
to a function is within an acceptable range.
</p>
<p><strong>See also:</strong> <a href="#XREFnarginchk">narginchk</a>, <a href="Raising-Errors.html#XREFerror">error</a>, <a href="Multiple-Return-Values.html#XREFnargout">nargout</a>, <a href="Defining-Functions.html#XREFnargin">nargin</a>.
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Next: <a href="Validating-the-type-of-Arguments.html" accesskey="n" rel="next">Validating the type of Arguments</a>, Up: <a href="Validating-Arguments.html" accesskey="u" rel="up">Validating Arguments</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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