⨳ macros and the data step ⨳

2012 Mar 14, Wednesday

recently, i had a need to use and update a macro variable within a data step. i wasn’t certain about the timing of things, so i threw together a simple test.

1. set a macro variable outside of a data step. (line 5742)
2. update the macro variable inside the data step. (line 5745)
3. use the (hopefully updated) macro variable to set a second variable within the data step. (line 5747)
4. put the value/calculation to the log window. (line 5748)

the log

5742   %let x=5;
5743   data _null_;
5744       %put before symput: &x;
before symput: 5
5745       call symput('x',10);
5746       %put after symput: &x;
after symput: 5
5747       xsquare=&X**2;
5748       put xsquare;
5749   run;


NOTE: Numeric values have been converted to character values at the places given by: (Line):(Column).
    5745:21
25
NOTE: DATA statement used (Total process time):


5750   %put outside data step: &x;
outside data step:           10

i’ve peppered the thing with %put statements to check on the values throughout the execution. and it does exactly what i didn’t want (line 5746). the data step used the original value rather than the updated value for the calculations.