CALL PRXSUBSTR Routine

Returns the position and length of a substring that matches a pattern

Category: Character String Matching

Restriction: Use with the PRXPARSE function

Syntax

CALL PRXSUBSTR ( regular-expression -id , source , position <, length >);

Arguments

regular-expression-id

specifies a numeric identification number that is returned by the PRXPARSE function.

source

specifies the character expression that you want to search.

position

is a numeric value that specifies the position in source where the pattern begins. If no match is found, CALL PRXSUBSTR returns zero.

length

specifies a numeric value that is the length of the substring that is matched by the pattern. If no match is found, CALL PRXSUBSTR returns zero.

Details

The CALL PRXSUBSTR routine searches the variable source with the pattern from PRXPARSE, returns the position of the start of the string, and optionally returns the length of the string that is matched. By default, when a pattern matches more than one character that begins at a specific position, CALL PRXSUBSTR selects the longest match.

For more information about pattern matching, see 'Pattern Matching Using SAS Regular Expressions (RX) and Perl Regular Expressions (PRX)' on page 260.

Comparisons

CALL PRXSUBSTR performs the same matching as PRXMATCH, but CALL PRXSUBSTR additionally enables you to use the length argument to receive more information about the match.

The Perl regular expression (PRX) functions and CALL routines work together to manipulate strings that match patterns. To see a list and short description of these functions and CALL routines, see the Character String Matching category in 'Functions and CALL Routines by Category' on page 270.

Examples

Example 1: Finding the Position and Length of a Substring

The following example searches a string for a substring, and returns its position and length in the string.

 data _null_;       /* Use PRXPARSE to compile the Perl regular expression. */    patternID = prxparse('/world/');       /* Use PRXSUBSTR to find the position and length of the string. */    call prxsubstr(patternID, 'Hello world!', position, length);    put position= length=; run;

The following line is written to the SAS log:

 position=7 length=5

Example 2: Finding a Match in a Substring

The following example searches for addresses that contain avenue, drive, or road, and extracts the text that was found.

 data _null_;     if _N_ = 1 then     do;        retain ExpressionID;           /* The i option specifies a case insensitive search. */        pattern = "/aveavenuedrdriverdroad/i";        ExpressionID = prxparse(pattern);     end;     input street .;     call prxsubstr(ExpressionID, street, position, length);     if position ^= 0 then     do;        match = substr(street, position, length);        put match:$QUOTE. "found in " street:$QUOTE.;     end;     datalines;  153 First Street  6789 64th Ave  4 Moritz Road  7493 Wilkes Place  ;  run;

The following lines are written to the SAS log:

 "Ave" found in "6789 64th Ave"  "Road" found in "4 Moritz Road"

CALL PRXSUBSTR Routine