topic Re: User-Defined Function that Does String Processing in SAS Programming

User-Defined Function that Does String Processing

daveconifer1 — Sun, 31 May 2020 16:00:53 GMT

I'm trying to create a user-define function that will work on character strings, so first I decided to learn the "plumbing" before developing the function.

I've created two user defined functions: DAVECASE(simply returns the length of a character string) and DAVESUM(returns the sum of the two integers passed in).

proc fcmp outlib=macros.userddefinedfunctions.davecase;  ** path/name for user-defined function **;

function davecase(instring);
 
      propstr = LENGTH(instring);

      return(propstr);

endsub;

function davesum(part1,part2);

      newsum = part1 + part2;

     return(newsum);

endsub;

Here is the code from which these two user-define functions are called:

data x;
 
     stringx = 'this is the untouched string';

	 daveway = DAVECASE(stringx);   ** gets tripped up, seems to expect integer **;

	 oldway = PROPCASE(stringx);     ** works fine **;

	 total = DAVESUM(2,3);       ** works fine;

	 run;

DAVESUM works perfectly, returning 5.

DAVECASE seems to get tripped up because somewhere along the line an integer is expected instead of a character string.

27         data x;
28         
29              stringx = 'this is the untouched string';
30         
31         	 daveway = DAVECASE(stringx);   ** gets tripped up, seems to expect integer **;
32         
33         	 oldway = PROPCASE(stringx);     ** works fine **;
34         
35         	 total = DAVESUM(2,3);       ** works fine;
36         
37         	 run;

NOTE: Character values have been converted to numeric values at the places given by: (Line):(Column).
      31:22   
NOTE: Invalid numeric data, stringx='this is the untouched string' , at line 31 column 22.
stringx=this is the untouched string daveway=1 oldway=This Is The Untouched String total=5 _ERROR_=1 _N_=1
NOTE: The data set WORK.X has 1 observations and 4 variables.
NOTE: DATA statement used (Total process time):

Is there something I need to do to indicate that the value being passed to DAVECASE is character?

Thanks,

...dave

Re: User-Defined Function that Does String Processing

ed_sas_member — Sun, 31 May 2020 16:09:52 GMT

Hi @daveconifer1

You need to specify that the argument is a character one by adding a '$' as follows in the function definition:

function davecase(instring $);

NB: for the second function, contrary to the SUM() function, the "+" operator does not handle missing values

Best,

Re: User-Defined Function that Does String Processing

daveconifer1 — Sun, 31 May 2020 16:28:49 GMT

Thanks, Ed! I was all over the documentation, or so I thought, but I didn't see that.

I got past that, and now my function has a new issue, so that's progress. This isn't as straightforward as i thought. I simplified DAVECASE to just return a copy of the argument:

function davecase(instring $);
 
      length propstr $ 80 ;

      propstr = instring;

      return(propstr);

endsub;

But I still get this:

149        data x;
150        
151             stringx = 'this is the untouched string';
152        
153        	 daveway = DAVECASE(stringx);   ** gets tripped up, seems to expect integer **;
154        
The SAS System

155        	 oldway = PROPCASE(stringx);     ** works fine **;
156        
157        	 total = DAVESUM(2,3);       ** works fine;
158        
159        	 run;

ERROR: Unable to convert a character value to a numeric value in function 'davecase' in statement number 3 at line 7 column 8.
       The statement was:
    0     (7:8)      _davecase_ = Move N<=C(propstr="this is the untouched string                                                    
")
ERROR: Exception occurred during subroutine call.
stringx=this is the untouched string daveway= oldway=This Is The Untouched String total=5 _ERROR_=1 _N_=1
NOTE: The data set WORK.X has 1 observations and 4 variables.

I'll look for more documentation and examples.

Thanks again,

...dave

Re: User-Defined Function that Does String Processing

ed_sas_member — Sun, 31 May 2020 16:37:42 GMT

Hi @daveconifer1

You can try to remove the LENGTH statement and adapt the FUNCTION definition as follows:

function davecase(instring $) $ 80;

-> in the parenthesis, you specify the input variable type ($)

-> after the parenthesis, you specify the output type and set the proper length (default = 8).

Best,

Re: User-Defined Function that Does String Processing

daveconifer1 — Sun, 31 May 2020 17:53:22 GMT

Thanks so much again, Ed! That worked perfectly, and makes perfect sense to me as well. I didn't like that LENGTH statement for the return argument, I was just trying stuff.

I appreciate your help. Now I can work on the function, since the plumbing is working.

...dave

Re: User-Defined Function that Does String Processing

ed_sas_member — Sun, 31 May 2020 17:59:43 GMT

Awesome!
Thank you @daveconifer1 😊