How to search products category wise in magento 1.9

In magento, Search is working fine when there are limited products and categories. But problem come when there are lots of products in different kind of categories.

And now customers are finding products with specific categories and tags. So if you want to increase sells you must need to provide category wise search for find product easily..

And good news is.. you can do this functionality easily. you need to replace code. Below code available for category wise search in magento :).

$category = Mage::getModel('catalog/category');
if(is_object(Mage::registry('current_category'))){
	$current_category_path=Mage::registry('current_category')->getPathIds();
}else{
	$current_category_path = array();
}
$category->load(Mage::app()->getStore()->getRootCategoryId());
$children_string = $category->getChildren();
$children = explode(',',$children_string);
$extra_options='';
foreach($children as $c){
	$selected = (in_array($c, $current_category_path))?'SELECTED':'';
	$extra_options.= '<option value="' . $c . '" ' . $selected . '>' . $category->load($c)->getName() . '</option>' . "\n";
}
?>
<form id="search_mini_form" action="<?php echo $this->helper('catalogSearch')->getResultUrl() ?>" method="get">
	<fieldset>
		<legend><?php echo $this->__('Search Site') ?></legend>
		<div class="mini-search">
			<input id="search" type="text" class="input-text" name="<?php echo $this->helper('catalogSearch')->getQueryParamName() ?>" value="<?php echo $this->helper('catalogSearch')->getEscapedQueryText() ?>" />
			<select name="cat" id="cat" class="input-text">
			<option value="">All Departments</option>
			<?= $extra_options ?>
		   </select>
			<input type="submit" value="Go" style="border: 1px solid #808080;" alt="<?php echo $this->__('Search') ?>" />
			<div id="search_autocomplete" class="search-autocomplete"></div>
			<script type="text/javascript">
			//<![CDATA[
				var searchForm = new Varien.searchForm('search_mini_form', 'search', '<?php echo $this->__('search site...') ?>');
				searchForm.initAutocomplete('<?php echo $this->helper('catalogSearch')->getSuggestUrl() ?>', 'search_autocomplete');
			//]]>
			</script>
		</div>
	</fieldset>
</form>

NOTE: Have tested in magento 1.9.4