Precision Issues with Java (& VB)...

[baden]

Explain why Java and VB for that matter don't return 0....

Something to do with storing the sum first and how it is stored????

------------- Java -----------------
class artest
{
public static void main(String[] args)
{
float x = 150.01f;
float y = 10.01f;
float z = x + y - 160.02f;

System.out.println("Z: "+ z);

if (z==0)
System.out.println("works"
else
System.out.println("doesn't work"

}
}
----------------------------

------------ VB : --------------

Option Explicit

Private Sub Form_Load()
Dim x As Double
Dim y As Double
Dim z As Double

x = 150.01
y = 10.01
z = x + y - 160.02


Print z
If z = 0 Then
MsgBox "This really works: " & z
Else
MsgBox "this sucks: " & z
End If

Text1.Text = z


End Sub

 

[palbano]

classic floating point problem, even in C++. The code below displays "breaks" when you run it.

float x = 150.01f;
float y = 10.01f;
float z = x + y - 160.02f;

if( z == 0.0f)
	cout << &quot;works&quot; << endl;
else
	cout << &quot;breaks&quot; << endl;

if you want to learn more about how/why google things like "floating point math" etc. There are tons of articles/papers on the subject.

-pete