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Hi, It has to do with the precision double and float types use to store the same number. Remember double type uses 64 bits and float type uses 32 bits

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Serdar Ozturk
Greenhorn

Joined: Aug 12, 2002
Posts: 14

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well, long is 64-bit wide and there is no loss of precision when you convert it to float first and then to double... on line 1 On line 2, we convert 32-bit integer to float and then to double and we loss some precision. Why dont we loss any precision on 64-bit long variable but on 32-bit integer? Serdar

Shishio San
Ranch Hand

Joined: Aug 29, 2002
Posts: 223

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Hi,

Widening primitive conversions do not lose information about the overall magnitude of a numeric value. Indeed, conversions widening from an integral type to another integral type and from float to double do not lose any information at all; the numeric value is preserved exactly. Conversion of an int or a long value to float, or of a long value to double, may result in loss of precision-that is, the result may lose some of the least significant bits of the value. In this case, the resulting floating-point value will be a correctly rounded version of the integer value,

Why dont we loss any precision on 64-bit long variable but on 32-bit integer?

Because Long.MAX_VALUE is much bigger than Integer.MAX_VALUE and both double and float won't have any difference in the precision used to represent it. As for Interger.MAX_VALUE, converting to double will preserve more signaficant number than converting it to float and this is again due to the number of bits of each type Hope this is clearer