function strpost,target,char,length,offset,occurance

;csee 16feb07
;this function returns the string following 'char' in 'target'
;i.e. if target = 'alpha = 1.05' then result = strpost(target,'=',3,2,1) = '.05'
;length is the number of characters included in the result
;offset is the number of interviening charcters between 'char' and 'result'
;occurance is which occurance of 'char' to use (i.e. 1=1st, 2=2nd, etc)

;target & char must be sting vaiables
;length, offset and occurance are intigers
;result is a sting
result='NUL'

;sort out missing parameters (defaults)...
if n_params() eq 2 then goto,p2
if n_params() eq 3 then goto,p3
if n_params() eq 4 then goto,p4
goto,p5

p2:
length=100	 ;default length of result is 100 characters
p3:
offset=0	 ;default offset is 0 (the next character after 'char')
p4:
occurance=1  ;default occurance is the 1st occurance in 'target' of 'char'
p5:

pos=-1	;start at the beginning.

;calculate pos of occurance...
for i=1,occurance do begin
 pos=strpos(target,char,pos+1)
 if pos eq -1 then begin
  print, 'There is(are) only ',sstr(i-1),' occurances of  "',char,'"  in  "',target,'"'
  print,'returning...'
  goto,exit
 endif
endfor

off2=strlen(char)
result=strmid(target,strpos(target,char,pos)+offset+off2,length)

exit:
return,result

end