replace the value 999 by a period '.' in a data set

[chriswong1386]

18.

The following raw data records contain the age of each individual customer. A value of 999 was used to represent a missing age value. Write an instream DATA step that will read the records and replace the value 999 with a period '.'

18 30 25 999 42 36 999

data ex18;
input age @@;
if age=999 then (I don't know what to put here);
datalines;
18 30 25 999 42 36 999
;
run;

help!

[Patrick · Accepted solution]

You've been almost there.

A dot is how SAS prints by default a missing value for a numerical variable. You can also use a dot in SAS syntax to assign missing to a SAS numerical variable.

data ex18;
  input age @@;
  /*if age=999 then (I don't know what to put here);*/
  if age=999 then age=.;
  datalines;
18 30 25 999 42 36 999
;
run;