Float cast reduces the value by 1

Question

When issuing (float) 33554329L, the result is 33554328. If the number then returns to the length, the value remains at 33554328, is there any explanation for this.

Using VS2005 in C ++ [not controlled]

Answer 1

The 32-bit float has 23 bits for the mantissa, which are 8,388,608 different values. This means that the accuracy is about 7 significant decimal digits. Your number has 8 decimal significant digits, so you see a loss of precision in the last significant digit.
Here's more info on the float view.

- 64 52 , 4 503 599 627 370 496 (16- ) , , 15-16 .

A decimal - , . # , , , ++. , , ++.

Answer 2

this:

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http://www.validlab.com/goldberg/paper.pdf

Answer 3

(3 +) .

0-1. , . , , ( , ).

: ( ).

Answer 4

The accuracy of the representation of various floating-point types depends on their size. For a 32-bit float, you can expect about 7 digits of accuracy. For double, it's about 16 digits.

I highly recommend reading floating point messages and various advantages and disadvantages. This will save you a lot of trouble in the long run, especially if things like comparisons don't work as you expect.