& Nbsp; what is the class? What functions should be used for filtering?

& Amp; nbsp; what type does it belong? What functions should be used for filtering? strip_tags can only filter html tags. I want to filter out escape characters such as & amp; nbsp;. Is there such a function ??, That function will not convert & amp; nbsp; & nbsp; PHPcode $ str = & quot; & amp; what type does it belong? What functions should be used for filtering,
Strip_tags can only filter html tags. I want to filter out the escape characters. Is there such a function ??

------ Solution --------------------
That function will not be converted

PHP code

$ Str = "&" <> "; echo preg_replace ('//','', $ str );