A prxchange issue

[whymath]

 Today, I have this bothering problem to ask for your help. Very preciate for your reading.

I an trying to change a datetime variable like '2020-05-18T9:27:58' to its regular form '2020-05-18T09:27:58', yes, that is the E8601DT format. So I code some tests like below:

data _null_;
	DTMC = '2020-05-18T9:27:58';
	ADTMC1 = prxchange('s/(.*?T)(\d:.*)/$10$2/',1,DTMC);
	ADTMC2 = prxchange('s/(.*?T)(\d:.*)/$1 0$2/',1,DTMC);
	ADTMC3 = prxchange('s/(.*?)T(\d:.*)/$1T0$2/',1,DTMC);
	put (ADTMC:) (=/);
run;

Here is the output:

ADTMC1=9:27:58
ADTMC2=2020-05-18T 09:27:58
ADTMC3=2020-05-18T09:27:58

As you can see, Only  ADTMC3 meet the desire.

I am very sure that  $10 in the first expression is trying to catch the 10th match group, which is failed, finally. $1 0$2 in the second expression successfully catch the first and second match group and add '0' between it, with an extra space.

May I modify the first expression to have the right result? Thanks for any hints.

[PGStats · Accepted solution]

You only need to match the substring(s) that you want to change. In your case, it is quite simple:

data _null_;
	DTMC = '2020-05-18T9:27:58';
	ADTMC1 = prxchange('s/T(\d):/T0\1:/', 1, DTMC);
	put (ADTMC:) (=/);
run;

[whymath]

Wonderful anwser.