function strnumber, st, val, hex = hexflg, NaN = nan, L64 = l64 ;+ ; NAME: ; STRNUMBER() ; PURPOSE: ; Function to determine if a string is a valid numeric value. ; ; EXPLANATION: ; A string is considered a valid numeric value if IDL can convert it ; to a numeric variable without error. ; CALLING SEQUENCE: ; result = strnumber( st, [val, /HEX] ) ; ; 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. double precision unless /L64 is set ; ; OPTIONAL INPUT KEYWORD: ; /HEX - If present and nonzero, the string is treated as a hexadecimal ; longword integer. ; /L64 - If present and nonzero, the val output variable is returned ; as a 64 bit integer. This to ensure that precision is not ; lost when returning a large 64 bit integer as double precision. ; This keyword has no effect on the function result. ; /NAN - if set, then the value of an empty string is returned as NaN, ; by default the returned value is 0.0d. In either case, ; an empty string is considered a valid numeric value. ; ; EXAMPLES: ; IDL> res = strnumber('0.2d', val) ; returns res=1 (a valid number), and val = 0.2000d ; ; NOTES: ; (1) STRNUMBER was modified in August 2006 so that an empty string is ; considered a valid number. Earlier versions of strnumber.pro did not ; do this because in very early (pre-V4.0) versions of IDL ; this could corrupt the IDL session. ; ; (2) STRNUMBER will return a string such as '23.45uyrg' as a valid ; number (=23.45) since this is how IDL performs the type conversion. If ; you want a stricter definition of valid number then use the VALID_NUM() ; function. ; HISTORY: ; version 1 By D. Lindler Aug. 1987 ; test for empty string, W. Landsman February, 1993 ; Hex keyword added. MRG, RITSS, 15 March 2000. ; An empty string is a valid number W. Landsman August 2006 ; Added /NAN keyword W. Landsman August 2006 ; Added /L64 keyword W. Landsman Feb 2010 ;- compile_opt idl2 if N_params() EQ 0 then begin print,'Syntax - result = strnumber( st, [val, /HEX, /NAN] )' return, 0 endif newstr = strtrim( st ) if keyword_set(NAN) then if newstr EQ '' then begin val = !VALUES.D_NAN return, 1 endif On_IOerror, L1 ;Go to L1 if conversion error occurs If ~keyword_set(hexflg) Then Begin val = double( newstr ) EndIf Else Begin val = 0L reads, newstr, val, Format="(Z)" EndElse if keyword_set(L64) then val = long64( newstr) return, 1 ;No conversion error L1: return, 0 ;Conversion error occured end