strcnt.pro
3.51 KB
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;
;+
; NAME:
; STRCNT
; PURPOSE:
; Count number of occurrences of a substring in a string.
; CATEGORY:
; text/strings
; CALLING SEQUENCE:
; num = strcnt(strn, substring, [pos])
; INPUTS:
; string -- The string in which to count occurences. in
; substring -- The substring to count occurrences of. in
; pos -- the position at which to begin the search. [in]
; If not supplied, start at beginning of
; string.
; KEYWORD PARAMETERS:
; /HELP -- Print useful message and return.
; OUTPUTS:
; num -- Number of occurances of substring in string. out
; COMMON BLOCKS:
; SIDE EFFECTS:
; NOTES:
; Overlapping occurances are not counted separately. For
; example, counting occurances of 'bb' in 'blah bbb' returns one
; occurance.
; EXAMPLE:
; MODIFICATION HISTORY:
; $Id: strcnt.pro,v 1.3 1996/06/14 20:00:27 mcraig Exp $
; $Log: strcnt.pro,v $
; Revision 1.3 1996/06/14 20:00:27 mcraig
; Updated Copyright info.
;
; Revision 1.2 1996/05/09 00:22:17 mcraig
; Added fast processing using BYTE arrays if we are counting occurences of
; a single character. Added error handling.
;
; Revision 1.1 1996/01/31 18:47:37 mcraig
; Initial revision
;
; RELEASE:
; $Name: Rel_2_1 $
;
; COPYRIGHT:
; Copyright (C) 1996 The Regents of the University of California, All
; Rights Reserved. Written by Matthew W. Craig.
; See the file COPYRIGHT for restrictions on distrubting this code.
; This code comes with absolutely NO warranty; see DISCLAIMER for details.
;-
FUNCTION Strcnt, strn, substrn, startpos, $
HELP=Help
; Return to caller if error.
On_error, 2
; Help user, if needed.
IF (n_params() LT 2) OR keyword_set(Help) THEN BEGIN
offset = ' '
print, offset+'Count number of occurrences of a substring in a string.'
print, offset+'num = strcnt(strn, substring, [pos])'
print, offset+'Inputs:'
print,offset+offset+'string -- The string in which to count occurences. in'
print,offset+offset+'substring -- The substring to count occurrences of. in'
print,offset+offset+'pos -- the position at which to begin the search. [in]'
print,offset+offset+' If not supplied, start at beginning of'
print,offset+offset+' string.'
print, offset+'Keywords:'
print,offset+offset+'/HELP -- Print useful message and return.'
print, offset+'Outputs:'
print,offset+offset+'num -- Number of occurances of substring in string. out'
return, -1
ENDIF
IF n_params() EQ 2 THEN startpos = 0
; return if we weren't really given a substring to search for. . .
IF strlen(substrn) EQ 0 THEN BEGIN
print, "Error: Can't count occurances of null string."
return, -1
ENDIF
; . . .or if we were told to start at the end of the string.
tmpstrn = strmid(strn, startpos, strlen(strn))
IF strlen(tmpstrn) EQ 0 THEN return, 0
; If looking for occurences of single character, process using BYTE
; array.
IF strlen(substrn) EQ 1 THEN BEGIN
tmpstrn = byte(TmpStrn)
count = n_elements(where(TmpStrn EQ (byte(substrn))(0)))
ENDIF ELSE BEGIN
count = 0L
pos = rstrpos(tmpstrn, substrn)
WHILE pos GE 0 DO BEGIN
count = count + 1
pos = rstrpos(tmpstrn, substrn, pos)
ENDWHILE
ENDELSE
return, count
END