sas, regex, numbers, substring, prxchange - regex

Question

I need help with the below code. I do not see how this is extracting the number from this address line text. When it (the pattern) says s/\D/ / I thought this replaces the digits with a space. I know the second part here is taking the substring up to the first space in the address line text. But, then I do not see how this is extracting the numbers. I pulled up the data set and it looks like this does work. Please help me understand how this is working.
DATA OUT.REQ_1_2_03;
SET OUT.REQ_1_2_02;
/* GET STREET NUMBER*/
PRE_RCV_ST_NB=PRXCHANGE('s/\D/ /',-1,SUBSTR(PRE_RCV_ADDRESSS_LINE_1,1,PRXMATCH('/\s/',PRE_RCV_ADDRESSS_LINE_1)));
POST_RCV_ST_NB=PRXCHANGE('s/\D/ /',-1,SUBSTR(POST_RCV_ADDRESSS_LINE_1,1,PRXMATCH('/\s/',POST_RCV_ADDRESSS_LINE_1)));
PRE_HOST_ST_NB=PRXCHANGE('s/\D/ /',-1,SUBSTR(PRE_HOST_ADDR_LINE_1,1,PRXMATCH('/\s/',PRE_HOST_ADDR_LINE_1)));
POST_HOST_ST_NB=PRXCHANGE('s/\D/ /',-1,SUBSTR(POST_HOST_ADDR_LINE_1,1,PRXMATCH('/\s/',POST_HOST_ADDR_LINE_1)));
RUN;

Answer 1

try to understand using an example
PRE_RCV_ADDRESSS_LINE_1 ="123hello Village st"
start from the left side of the code.
first use prxmatch and it finds first space(\s)that comes 123hello
do substr till that space and you get 123hello
then remove prxchanges to replace \D (that is anything other than digit) and
is converted to 123
to sum it up by example
"123hello Village st" -- find space(\s) by prxmatch and substring till space gives "123hello"
"123hello" is changed to "123" by prxchange which replaces anything other than digit(\D) .
/* run this step to understand it better*/
data want ;
PRE_RCV_ADDRESSS_LINE_1 = "123hello Village st";
test1= SUBSTR(PRE_RCV_ADDRESSS_LINE_1,1,PRXMATCH('/\s/',PRE_RCV_ADDRESSS_LINE_1));
PRE_RCV_ST_NB= PRXCHANGE('s/\D//',-1,SUBSTR(PRE_RCV_ADDRESSS_LINE_1,1,PRXMATCH('/\s/',PRE_RCV_ADDRESSS_LINE_1)));
run;