function strnumber, st, val ;+ ; NAME: ; STRNUMBER ; ; PURPOSE: ; Function to determine if a string is a valid numeric value. ; ; CALLING SEQUENCE: ; result = strnumber( st, [val] ) ; ; INPUTS: ; st - any IDL scalar string ; ; OUTPUTS: ; 1 is returned as the function value if the string st has a ; valid numeric value, otherwise, 0 is returned. ; ; OPTIONAL OUTPUT: ; val - (optional) value of the string. real*8 ; ; WARNING: ; (1) In V2.2.2 there was a bug in the IDL ON_IOERROR procedure that ; will cause the following statement to hang up IDL ; ; IDL> print,'' + string( strnumber('xxx') ) ; This bug was fixed in V2.3.0 ; (2) In V2.3.2, an IDL bug is seen in the following statements ; IDL> st = 'E' ; IDL> q = strnumber(st) & print,st ; The variable 'st' gets modified to an empty string. This problem ; is related to the ambiguity of whether 'E' is a number or not ; (could be = 0.0E). This bug was fixed in V3.0.0 ; (3) STRNUMBER was modified in February 1993 to include a special ; test for empty or null strings, which now returns a 0 (not a ; number). Without this special test, it was found that a ; empty string (' ') could corrupt the stack. ; HISTORY: ; version 1 By D. Lindler Aug. 1987 ; test for empty string, W. Landsman February, 1993 ; Converted to IDL V5.0 W. Landsman September 1997 ;- if N_params() EQ 0 then begin print,'Syntax - result = strnumber( st, [val] ) return, 0 endif newstr = strtrim( st ) if ( newstr EQ '' ) then return, 0 ;Empty string is a special case On_IOerror, L1 ;Go to L1 if conversion error occurs val = double( newstr ) return, 1 ;No conversion error L1: return, 0 ;Conversion error occured end
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|Last modified on 2nd Mar 2009 by Richard Massey.|