CODEWITHSUNDEEP
kotlin
Alf Moh
Alf Moh

Reputation: 7437

Large numbers conversion to Byte in Kotlin

Why does a double of 65555 converted to byte produce a result of 19 in Kotlin?

Upvotes: 3

Views: 397

Answers (3)

hotkey
hotkey

Reputation: 147991

That's because of a numerical conversion from a wider type to a type of a smaller size. The Double (IEEE 754 double precision number) has its integral part factored to the powers of two as
65555 = 217 + 24 + 22 + 20 = 65536 + 16 + 2 + 1, which is stored in binary form as (higher bits to lower):

 ‭... 0 1  0 0 0 0 0 0 0 0  0 0 0 1 0 0 1 1‬

When this number is converted to Byte, only its lowest 8 bits are retained:

 ... _ ‭_  _ _ _ _ _ _ _ _  0 0 0 1 0 0 1 1‬

And that results into 24 + 22 + 20 = 16 + 2 + 1 = 19.

Upvotes: 9

Todd
Todd

Reputation: 31710

Because when you convert 65555 (or 65555.0) to a binary representation it takes more than one byte. So calling .toByte() takes the lowest one, which is 19.

65555 -> Binary == 1 00000000 00010011
                   ^ ^^^^^^^^ ^^^^^^^^
                   1     0       19

Upvotes: 3

Miha_x64
Miha_x64

Reputation: 6373

Double 65555.0 gets converted to integer 65555 which is 0x10013. Conversion to Byte takes lower byte which is 0x13 (19 decimal).

Upvotes: 1

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