How to wordpress get categories list easily.You can get categories list by wp_list_categories() core function.It is listing as categories names as a list.

$catagoriesArr = explode("
",wp_list_categories('title_li=&echo=0&depth=1&style=none'));
$catagoriesCount = count($catagoriesArr)-1;// array size
$catagoryName = '
';
for ($i=0; $i<$catagoriesCount; $i++){
  $catagoryName .= '
'.$catagoriesArr[$i].'
';
}
$catagoryName .= '
';
echo $catagoryName;

wordpress get categories list as two columns

",wp_list_categories('title_li=&echo=0&depth=1&style=none'));
$catagoriesCount = count($catagoriesArr)-1;// array size
for ($i=0; $i<$catagoriesCount; $i++){
	 if ($i%2==1){
		$col_left = $col_left.'
'.$catagoriesArr[$i].'
';
	 }
	 else {
		$col_right = $col_right.'
'.$catagoriesArr[$i].'
';
	 }
}
?>

	


    

This is a another way to get categories list or full details.

echo '
';
$categories = get_categories();
foreach ($categories as $cat) {
	echo '
'.$cat->cat_name.'
';
}
echo '
';

How can I get posts or pages in specific category

No need to worry about to get categories details.:p
Navigate and open the following file.There are many functions to get category details.
/wp-includes/category-template.php