hexadecimal | Julia Evans

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hexadecimal

## binary numbers are hard to read

1101010111011001 1101010111001001

it's hard to tell if these are different!

Also, binary numbers are too long: the number 4,000,000,000 is this in binary: 11101110011010110010100000000000

## decimal has problems too

11010101 = 213
11000101 = 197

These are easier to read, but 213 and 197 look COMPLETELY different, even though the binary numbers only differ by 1 bit.

This is bad if you're trying to think
about the binary representation.

## hexadecimal makes binary data more readable

Every hexadecimal digit represents 4 bits. So 1 byte (8 bits) is 2 digits.

1101 0101 1100 0101

d 5 c 5

* 11010101 = d5
* 11000101 = c5

it's much easier to
see the similarities!

## there are 16 hex digits

* decimal binary hex
* 0000 0 0
* 0001 1 1
* 0010 2 2
* 0011 3 3
* 0100 4 4
* 0101 5 5
* 0110 6 6
* 0111 7 7
* 1000 8 8
* 1001 9 9
* 1010 10 a
* 1011 11 b
* 1100 12 c
* 1101 13 d
* 1110 14 e
* 1111 15 f

## `0x` means it's hex

person 1: "the ASCII code for space is 0x20"

person 2: "that starts with `0x`, so it means 32 and not 20!"

## things hexadecimal is used for

* color codes! (eg 0xFF00FF)
* memory addresses!
* displaying binary data! (like with `hexdump`)
)

0 Like 0 27 Jan 2023 at 16:58 | Open on social.jvns.ca

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