Preg_match空字符串

So, I have to read a text file and get certain fields like name*: xxxxx, and save the xxx in a new file.. I've been using Regex to get the xxxx and save them in the text file and its working well, the only problems is that when i find empty fields like name*: The preg_match skips them, and the result i want is to save them as empty spaces " ".

here is my code and a bit of the file i need to fix the problems:

else if (preg_match("/^Data\sde\semiss.o\sdo\sBI\:(.+)/", $line, $matches)) {
            //print_r($matches);
            $total[$titular][]=$matches[1] . ";";
    }

Data de emissão do BI:

Arquivo de Identificação: FUNCHAL

Nº de Contribuinte*: 12341234

I need to get a $match equal to the spaces after "Data de emissão do BI:" so i can fill an empty cell (in a csv file)

Change + to *:

preg_match("/^Data\sde\semiss.o\sdo\sBI\:(.*)/", $line, $matches)

+ matches 1 or more of the preceding RE, * matches 0 or more of the preceding RE. So this allows empty strings.