Nicholas Barrington wrote:
> Float f = 4 / 8;
> Integer i = f * 100;
> Integer i = ((float)(4 / 8)) * 100;
This code won't compile. Even if the java compiler could compile it, it
would still produce the wrong answer for the same reason. This is because 4
/ 8 is still 0, so f would contain 0.0, and i would still be 0.
The concept is correct that floating point arithmetic needs to be used.
Binary operators like / and * will convert their operands if they need to.
So, if both operands are integer, java will do integer math, but if one is a
float and the other is integer, java will convert the integer to a float and
perform floating point arithmetic.
Try this instead:
<%=(int)(((double)4)/8*100)%>
I know this is more complicated, but it works. It converts 4 into a float,
so the / has to convert the 8 into a float as well. The result of a float
divide is a float, so the * has to convert its other operand, 100 to a
float. The result is a float 50, which you may want to convert back to an
int with the (int) cast. A simpler way to accomplish this is to just store
the 4 or 8 in a float variable.
Larry
-----Original Message-----
From: Nicholas Barrington [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, November 24, 1999 4:13 PM
To: [EMAIL PROTECTED]
Subject: Re: <%=numresponses/numrequests*100 %>
James,
4 / 8 *is* 0, at least the integer part is 0, with a remainder (modulus) of
.5. Some compilers try to compensate for humans using incorrect data types
in arithmetic calculations by rounding based on the 0.0 to 0.4 round down,
0.5 to 0.9 round up method. Some don't; they assume we code what we mean
and only specifiy integers if we are interested in integer precision. If
you need to divide numbers and want more accuracy in your results, try using
float or double style data types for your arithmetic.
E.G.
Float f = 4 / 8;
Integer i = f * 100;
or
Integer i = ((Float)(4 / 8)) * 100;
-----Original Message-----
From: Griggs, James [ mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]> ]
Sent: Thursday, November 25, 1999 5:25 AM
To: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
Subject: <%=numresponses/numrequests*100 %>
Any reason the following statement would always produce a 0?
Other expressions work just fine when the result of the first calculation is
above 1 (eg: 5+2*100). Is this a rounding issue ???
<%=4/8*100 %>
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