> This is probably simple, but I must be looking in
> the wrong places ... I'm trying to do what the strtod()
> function does for me in C: Find the longest prefix of a
> string that looks like a number, produce its numeric
> value, and tell me where the unconverted suffix starts.
>
> This sounds like a job for DecimalFormat.parse(), but
> I can't get it to accept all the things I'd like it to
> consider as numbers. Constructed from the pattern "0E0"
> or "#E0" (or "0e0" or "#e0"), a DecimalFormat will happily
> parse "1" and "1.2" and ".2" and "-1.2E3", and "1E-3", but
> it rejects "+1" and "1e3" and "1E+3". Some of the rejections
> are outright failures ("+1" gives a null result, for example),
> while others are incomplete conversions ("1E+3" produces the
> value 1 with "E+3" as the unconverted suffix).
>
> Now, Double.valueOf() happily accepts and does the
> right thing with all these forms -- but it insists on
> converting the entire string, not just a prefix. It'd
> be possible to do a sort of binary search to find the
> longest prefix that doesn't provoke NumberFormatException,
> but my stomach turns at the thought of such vileness.
>
> Please help an old C programmer who's trying to reform:
> Where do I find the Java equivalent of strtod()?
I'd imagine the string will not be very long. Assuming you don't have to
convert a lot of numbers, use a for loop and the index method to see if
the current character is not a number, decimal place or the letter E.
Break out of the loop when you find the non-double character. Pass the
substring into Double.valueOf(). Use a try/catch for the
NumberFormatException because the simple for loop will not check for
thing like "1E+3Everything". This will pass "1E+3E" to the valueOf method.
--
Send e-mail to: darrell dot grainger at utoronto dot ca
Re: Desperately seeking strtod() ... >>converting the entire string, not just a prefix. ...>>longest prefix that doesn't provoke NumberFormatException,... > Break out of the loop when you find the non-double character. ... (comp.lang.java.help)
extension_pack ... It is used to set upper loop -- limits for non-deterministic values thus avoiding the use of access -- types and enabling the functions to be used for synthesizeable code. ... DivisorVal: integer) return std_logic_vector; function "/"(DividendVal: string; DivisorVal: integer) return std_logic_vector; ... for loopVar in 0 to slvVal'length/4-1 loop ... end loop; if then return not resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to else return resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to end if; ... (comp.lang.vhdl)
extension_pack ... It is used to set upper loop -- limits for non-deterministic values thus avoiding the use of access -- types and enabling the functions to be used for synthesizeable code. ... DivisorVal: integer) return std_logic_vector; function "/"(DividendVal: string; DivisorVal: integer) return std_logic_vector; ... for loopVar in 0 to slvVal'length/4-1 loop ... end loop; if then return not resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to else return resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to end if; ... (comp.lang.vhdl)
extension_pack ... It is used to set upper loop -- limits for non-deterministic values thus avoiding the use of access -- types and enabling the functions to be used for synthesizeable code. ... DivisorVal: integer) return std_logic_vector; function "/"(DividendVal: string; DivisorVal: integer) return std_logic_vector; ... for loopVar in 0 to slvVal'length/4-1 loop ... end loop; if then return not resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to else return resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to end if; ... (comp.lang.vhdl)
extension_pack ... It is used to set upper loop -- limits for non-deterministic values thus avoiding the use of access -- types and enabling the functions to be used for synthesizeable code. ... DivisorVal: integer) return std_logic_vector; function "/"(DividendVal: string; DivisorVal: integer) return std_logic_vector; ... for loopVar in 0 to slvVal'length/4-1 loop ... end loop; if then return not resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to else return resultVar; -- "width mismatch" errors here are due to improper sizing of the vector that this function is assigned to end if; ... (comp.lang.vhdl)
