Very interesting test! I could not understand at first why multiplying with an even integer factor would introduce rounding errors. So it seemed, but when I went one step back and ignored the multiplication I saw: the value itself is not expressible as a fixedpoint binary number.

So there are two ways to look at it (numerically and as a string): 

$ perl -wE '$x=35784.45; printf "%.15f\n%s", $x, $x;'
35784.449999999997090
35784.45

[download]

Since now I always assumed the string representation were made from the numerical representation thus giving the same output. That was obviously wrong.

Update:

A second counter test 

$ perl -wE '$x=35784.449999999997090; printf "%.15f\n%s", $x, $x;'
35784.449999999997090
35784.45

[download]
reveals: the string representation always uses some rounding.

In reply to Re^4: Strange int() result by hexcoder
in thread Strange int() result by menth0l

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