PHP str_replace与file_put_contents,缓存交互

Not sure why but having an issue here, this is the last line in my PHP, through a global.php file, I'm saving scraped data in the cache folder. In the below situation, I'm saving it as "s&pcurrent." In my output, I'm getting a "+" that I don't want, which is from the source content. Likewise, I created a str_replace to get rid of the + with a blank space ' '

However, it doesn't work, I must be formatting it wrong somehow. Any tips? Thanks so much.

file_put_contents(globalVars::$_cache_dir . "s&pcurrent", str_replace('+', ' 
', $ret_[0]);