In c# double type how can i set the number of digits after the point, i need only 4. thank you.
+3
A:
You can't. Binary floating point doesn't work like that. You can format a double that way (e.g. using "f4" as the format string), but if you're dealing with values which have a natural number of decimal places, then you should probably be using decimal instead. Could you give us more information about what your values represent?
Jon Skeet
2010-02-20 18:57:10
i m doing an equality between 2 points's x and there values are5.0000 and 4.999999996and i need it te be true
Bass
2010-02-20 19:02:00
@Bass: If you're only doing an equality test, then nobugz's answer is probably the right way to go. I would still consider whether you want to use decimal instead though - it depends on the kind of values you've got.
Jon Skeet
2010-02-21 07:28:59
A:
You can't set the number of digits after the point on the double directly.
You can change the string representation of the double using a format string.
One example would be:
string.Format("{0:0.####}", number);
Or as Jon Skeet points out:
number.ToString("f4")
John Weldon
2010-02-20 18:58:23
+2
A:
Use this to compare two floating point numbers to 4 digits in the fraction:
if (Math.Abs(a - b) < 1E-4) {
// close enough
//...
}
Hans Passant
2010-02-20 19:48:55
If you want to be absolutely sure they are equal then it should be Double.epsilon rather than 1e-4. If you want to say they are 'close enough' equal then you're code is fine
zebrabox
2010-02-20 20:25:59
Double.Epsilon cannot work as-is, it is far too small. A proper epsilon is something like a * 1E-15 but that has to be incremented for errors accumulated by each FP operation.
Hans Passant
2010-02-20 20:46:30