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While reading someone else code, I noticed that they were using hexadecimal numbers instead of regular base 10. What is the added benefit of using hexadecimal in code (or even binary for that matter).

For example:


enum Behavior
{
Flee     = 0x00001,
Seek     = 0x00002,
Wander = 0x00003

}



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8 is bit 4, 3 is bits 1 and 2, 128 is bit 8

You're off by one in bit number.

Lowest bit is bit number 0, which is 1 or 0x01, which is also 2^0, or 1 << 0.

By starting bit numbers by 0, the power, the shift, and the number of zeroes right of the 1 (ie the zeroes shifted in) all match.

dec =  hex = shift = power = bits
1 = 0x01 = 1 << 0 = 2^0 = 0001
2 = 0x02 = 1 << 1 = 2^1 = 0010
4 = 0x04 = 1 << 2 = 2^2 = 0100
8 = 0x08 = 1 << 3 = 2^3 = 1000


If you start counting at 1, you get "1 << (1-1)", and "2^(1-1)" in the first line which is more cumbersome to get right all the time.

Edit:

As others have noted, hex is mostly useful if you are interested in bits than the numeric value.

In fact, I read hex numbers always as bit patterns, and not as hex number. For example, "0xDA" I don't read as hex "D" and "A", I read it as bit patterns "1101" and "1010", I see the bit patterns expressed by the hex digits.

Edited by Alberth

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My personal preference is to only use hex to show that I'm caring more about the bits within the variable than the value itself.

For instance:
char some_flags = 0x0D; // <- This is more descriptive to me than...
char some_flags = 13; // ... this. The bits are important, the value is not. I see 0x0D as 00001101, not '13'. I see '13' as a number and not a string of bits.

Edited by MarkS

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While reading someone else code, I noticed that they were using hexadecimal numbers instead of regular base 10. What is the added benefit of using hexadecimal in code (or even binary for that matter).

For example:


enum Behavior
{
Flee     = 0x00001,
Seek     = 0x00002,
Wander = 0x00003

}



The reason it would be used in an enum like your example is when the programmer wants to combine the enum values.

When using powers of two the values look like this:

0x1 = 0001
0x2 = 0010
0x4 = 0100
0x8 = 1000

So if we have:

enum Behavior {
Patrol = 0x1,
Seek   = 0x2,
Talk   = 0x4,
Run    = 0x8
}


then behaviors can be combined by OR-ing the values.

For example if an NPC is patrolling and talking:

Behavior CurrentBehavior = Behavior.Patrol | Behavior.Talk;  // CurrentBehavior is 0001 | 0100 -> 0101

or we can find out if a behavior is currently set by AND-ing the values:

if ((CurrentBehavior &  Behavior.Talk) == Behavior.Talk)   // ((0101 & 0100) == 0100) -> true

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The reason it would be used in an enum like your example is when the programmer wants to combine the enum values.

But look closely at the example. ;)


enum Behavior
{
Flee     = 0x00001, // Going to assume there are missing digits here.... In binary: 00000001
Seek     = 0x00002, //In binary: 00000010
Wander = 0x00003 // In binary: 00000011

}

In this case, Behavior.Flee | Behavior.Seek = Behavior.Wander. Behavior.Flee | Behavior.Wander = Behavior.Wander. Behavior.Seek | Behavior.Wander = Behavior.Wander. They have to be used separately, otherwise you just end up wandering. Edited by MarkS

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