%SUBSTR and %QSUBSTR

%SUBSTR and %QSUBSTR

Produce a substring of a character string

Type: Macro functions

See also: %NRBQUOTE

Syntax
Details
Comparisons
Examples
	Example 1: Limiting a Fileref to Eight Characters
	Example 2: Storing a Long Macro Variable Value In Segments
	Example 3: Comparing Actions of %SUBSTR and %QSUBSTR

Syntax

%SUBSTR (argument,position<,length>)

%QSUBSTR (argument,position<,length>)

argument: is a character string or a text expression. If argument might contain a special character or mnemonic operator, listed below, use %QSUBSTR.
position: is an integer or an expression (text, logical, or arithmetic) that yields an integer, which specifies the position of the first character in the substring. If position is greater than the number of characters in the string, %SUBSTR and %QSUBSTR issue a warning message and return a null value. An automatic call to %EVAL causes n to be treated as a numeric value.
length: is an optional integer or an expression (text, logical, or arithmetic) that yields an integer that specifies the number of characters in the substring. If length is greater than the number of characters following position in argument, %SUBSTR and %QSUBSTR issue a warning message and return a substring containing the characters from position to the end of the string. By default, %SUBSTR and %QSUBSTR produce a string containing the characters from position to the end of the character string.

Details

The %SUBSTR and %QSUBSTR functions produce a substring of argument, beginning at position, for length number of characters.

%SUBSTR does not mask special characters or mnemonic operators in its result, even when the argument was previously masked by a macro quoting function. %QSUBSTR masks the following special characters and mnemonic operators:

& % ' " ( ) + - * / < > = ¬ ^ ~ ; , blank
AND OR NOT EQ NE LE LT GE GT

Comparisons

%QSUBSTR masks the same characters as the %NRBQUOTE function.

Examples

Example 1: Limiting a Fileref to Eight Characters

The macro MAKEFREF uses %SUBSTR to assign the first eight characters of a parameter as a fileref, in case a user assigns one that is longer.

%macro makefref(fileref,file);
   %if %length(&fileref) gt 8 %then
       %let fileref = %substr(&fileref,1,8);
   filename &fileref "&file";
%mend makefref;

%makefref(humanresource,/dept/humanresource/report96)

SAS sees the statement

FILENAME HUMANRES "/dept/humanresource/report96";

Example 2: Storing a Long Macro Variable Value In Segments

The macro SEPMSG separates the value of the macro variable MSG into 40-character units and stores each unit in a separate variable.

%macro sepmsg(msg);
   %let i=1;
   %let start=1;
   %if %length(&msg)>40 %then
      %do;
          %do %until(%length(&&msg&i)<40);
             %let msg&i=%qsubstr(&msg,&start,40);
             %put Message &i is: &&msg&i;
             %let i=%eval(&i+1);
             %let start=%eval(&start+40);
             %let msg&i=%qsubstr(&msg,&start);
          %end;
          %put Message &i is: &&msg&i;
      %end;
   %else %put No subdivision was needed.;
%mend sepmsg;

%sepmsg(%nrstr(A character operand was found in the %EVAL function 
or %IF condition where a numeric operand is required.  A character 
operand was found in the %EVAL function or %IF condition where a 
numeric operand is required.));

Executing this program writes these lines to the SAS log:

Message 1 is: A character operand was found in the %EV
Message 2 is: AL function or  %IF condition where a nu
Message 3 is: meric operand is required.  A character
Message 4 is: operand was  found in the %EVAL function
Message 5 is:  or %IF condition where a numeric operan
Message 6 is: d is required.

Example 3: Comparing Actions of %SUBSTR and %QSUBSTR

Because the value of C is masked by %NRSTR, the value is not resolved at compilation. %SUBSTR produces a resolved result because it does not mask special characters and mnemonic operators in C before processing it, even though the value of C had previously been masked with the %NRSTR function.

%let a=one;
%let b=two;
%let c=%nrstr(&a &b);

%put C: &c;
%put With SUBSTR: %substr(&c,1,2);
%put With QSUBSTR: %qsubstr(&c,1,2);

Executing these statements writes these lines to the SAS log:

C: &a &b
With SUBSTR: one
With QSUBSTR: &a

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