Issue or my lack of understanding: Sum statement with RETAIN vs NO RETAIN handling missing values

[novinosrin]

Is the below an Issue or my lack of understanding: Sum statement with RETAIN vs NO RETAIN handling missing values

data _null_;
  retain k;
  b=.;
  k+b;
  put k=;
run;


data _null_;
/*  retain k;*/
  b=.;
  k+b;
  put k=;
run;

Can somebody explain and help me why the difference in the results of K in the above 2 programs plz? Thank you in advance! 

LOG-

70
71   data _null_;
72     retain k;
73     b=.;
74     k+b;
75     put k=;
76   run;

k=.
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds


77
78
79   data _null_;
80   /*  retain k;*/
81     b=.;
82     k+b;
83     put k=;
84   run;

k=0
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds

[data_null__ · Accepted solution]

---

@novinosrin wrote:

Is the below an Issue or my lack of understanding: Sum statement with RETAIN vs NO RETAIN handling missing values

data _null_;
  retain k;
  b=.;
  k+b;
  put k=;
run;


data _null_;
/*  retain k;*/
  b=.;
  k+b;
  put k=;
run;

Can somebody explain and help me why the difference in the results of K in the above 2 programs plz? Thank you in advance! 

LOG-

70
71   data _null_;
72     retain k;
73     b=.;
74     k+b;
75     put k=;
76   run;

k=.
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds


77
78
79   data _null_;
80   /*  retain k;*/
81     b=.;
82     k+b;
83     put k=;
84   run;

k=0
NOTE: DATA statement used (Total process time):
      real time           0.00 seconds
      cpu time            0.00 seconds

---

In your first data step you RETAIN K and implicitly initialize to missing.

[novinosrin]

Right, got it sorry my bad!

[Ksharp]

Sum statement include another implicated statement (i.e. retain k 0 😉