[Networking Series 2/3] Bits, Bytes and more

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[Networking Series 2/3] Bits, Bytes and more

Postby Dennis Kuypers » Wed Jul 25, 2018 10:38 pm

If you break down how a computer works, it's basically just ones and zeros (power on OR power off). We can express this using the binary system.
Mostly we are interested in larger numbers than just 0 or 1 can express on their own. The smallest unit we mostly talk about is called...

A Byte
A byte consists of 8 bits. The largest number we can get when using 8 bits (or 8 digits in the binary system) is 111111112 = 255. If we add the 0 we have 256 possible values. The hexadecimal system offers a convenient way to express one byte (for example 255) as 0xFF. Now a byte can only "store" values from 0-255 - what if we want higher values? We can use...

Integers
An Integer (lat. for "whole" as in "whole numbers"/"no fractions") comes in different sizes, we usually have either one byte - which we just call a byte - or we combine multiple bytes:
  • 2 bytes = 16 bits = "short" or "int16"
  • 4 bytes = 32 bits = just "int" or "int32"
  • 8 bytes = 64 bits = "int64"

Now we might want to store or transmit negative values. This can be done by using the first bit as the sign (first bit decides wether the number is positive or negative). That leaves us with 7bits for the actual value when using bytes, 15bits when using a "short", etc...
We call these signed or unsigned Please note that the "default" version of each integer is the signed version. The only exception to this rule is the byte which is unsigned. If you want to express the "signedness" of the datatype use these names:

signed: "sbyte" or "int8", "short" or "int16", "integer" or "int32", "int64"
unsigned: "byte" or "uint8", "ushort" or "uint16", "uint" or "uint32", "uint64"

Bonus: Decimal numbers
These are called "floats" and the most used one is called a "double". They are rather complicated compared to integers - if you're interested, there are many good resources on the web.
Dennis Kuypers
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