double precision

[yukeshean]

dear all,
let say i have a number in string form. The number is 78.18 but is in Sring type. I have to get the number for 78.18 * 11 , which is in number data type, not String type. Therefore, i use Double.parseDouble()....but what i got at last is 859.9000000...01. Why? If i want to get the answer in 859.90 (in 2 precision), how should i do?

Thanks.

yukeshean
fyshean@hotmail.com

 

[klein]

hi,
this code work good,
double d1 = java.lang.Double.valueOf("78.18&quot.doubleValue();
double d2 = 11;
double sum = d1 * d2;
yehuda.

 

[yukeshean]

Dear klein,
I'm sorry ...I still got a number with more than 2 precision (e.g: 98.110000000000078).
Why???

Thanks

 

[stillflame]

the toString method of a double number returns a string which is as precise as the number can get, and as always with floating point arithmetic, there will be errors, which result in tini tiny little decimals being tacked onto the number. if you just want 2 decimal places, multiply the number by 100, cast it into an 'int', and then print all but the last to digits, a '.', and the rest of the number:[tt]
double num = java.lang.Double.valueOf(string).doubleValue();
int temp = (int)(num * 100.0);
String double = (new Integer(temp)).toString();
String answer = double.substring(0, double.length() - 2) +
"." + double.substring(double.length() - 2
double.length());
[/tt]
this code is untested, but should illustrate how to do it.
good luck. "If you think you're too small to make a difference, try spending a night in a closed tent with a mosquito."