I'm using `parse_str` to get an array from a string, which is like: 

```
$str='a=123&b=456&Signature=aaaa/bbb+i8=&Satus=bbbb';

```

I noticed that the function `parse_str` does convert plus to space, but how can I avoid this things.

new edit:  

The `$str` to a value that I get from a string which is like this: 

```
YT0xMjMmYj00NTYmU2lnbmF0dXJlPWFhYWEvYmJiK2k4PSZTYXR1cz1iYmJi

```

I get the string and make base64\_decode,then get the `$str`.