How to use SUBSTR to create another variable?

[Nietzsche]

hi all, 

If run the following code, I can create a new column "new_val" that is the sub of the original value, which returns 98.

data news;
val='06MAY98';
new_val=substr(val, 6, 2);

proc print data=news; run;

This time I want to replace the year 98 with 99, so I wrote this following code, but instead of getting '06MAY99', I got a 0. 

data news;
val='06MAY98';
new_val=substr(val, 6, 2) = 99;

proc print data=news; run;

is there any way to fix this?

[MarkusWeick]

Hi @Nietzsche , in your example you can fix it with

data news;
val='06MAY98';
new_val=cat(substr(val, 0, 5),99);

proc print data=news; run;

two remarks:

1. "substr" is a function to get a substring not to change a substring.

2. A general better approach might be to work with dates instead of character value resembling dates.

[LinusH]

As @MarkusWeick suggest, use a numerical date formatted column for this.

data news;
   val = '06May1998'd;
   new_val = intnx('YEAR',val, 1, 'SAME');
   format val new_val date9.;
run;

[Ksharp]

Use left-side SUBSTR() function:

data news;
val='06MAY98';
substr(val, 6, 2) = 99;

proc print data=news; run;

[MarkusWeick]

Thanks for the left-side SUBSTR() function

[FreelanceReinh · Accepted solution]

Hi @Nietzsche,

Your result 0 is the Boolean value saying that the equality 98 = 99 is false. (The character string substr(val, 6, 2)='98' was automatically converted to the number 98, see the corresponding note in the log.)

The SUBSTR (left of =) function modifies the value of the variable in the first argument, so you should create NEW_VAL first with the old value and then modify it:

data news;
val='06MAY98';
new_val=val;
substr(new_val, 6)='99';
run;

Alternatively, you could define NEW_VAL like this

new_val=substr(val, 1, 5)||'99';

using the SUBSTR (right of =) function. But then the length of NEW_VAL would be 9 (=length(val)+length('99')) by default rather than 7 with the previous method. The preliminary assignment statement new_val=val or a LENGTH statement could avoid that.