Why is 0x hex

The hexadecimal system can represent much larger numbers using fewer characters, and it closely resembles binary numbers.

Hexadecimal numbers are usually prefixed with the characters '0x' which are not part of the number. A single hexadecimal digit can represent four binary digits! So how do we convert between number systems? First consider how we determine the value of a decimal number. The base of a decimal number is Each digit has to be scaled according to its place within the number.

The scale of the digit is the base of the number system raised to the power of the digit's location in the number. So each number is scaled, and then all of the scaled digits are added to find the total value of the number.

The same method can be used to find the value of a binary number. The base of the binary system is 2 the prefix 0b is often used in code to indicate that the number is in the binary format. What a completely inefficient way of typing a number! But we can represent the same binary number using only 2 hexadecimal digits. First though, we'll start by converting a hexadecimal hex number to decimal like we did for a binary number.

How about 0xB5? Wait, what?! The prefix 0x is used in code to indicate that the number is being written in hex. Ask Question. Asked 11 years, 6 months ago. Active 3 months ago. Viewed k times. Thomas Bratt Now I realize that the title and the text ask two entirely different questions. Most replies focus on the question in the title.

The answer to the question in the text is simply "it does not mean anything - it is merely a prefix telling the compiler that the integer is written in hexadecimal". To be pedantic, one might also interpret the question in the title in two different ways: 1 "Why are hexadecimal numbers prefixed as 0x, as opposed to any other prefix or indicator? Surely the compiler will recognize 58A as a hexadecimal number even without the prefix?

Why the prefix 0x denotes hex number, instead of 0h? Add a comment. Active Oldest Votes. C is a descendant of C, so it inherits the syntax. They couldn't use any number as a second digit indicator except 8 or 9 , and neither holds any significance related to hexidecimal so a letter is a must. And that leaves either 0h or 0x H e X idecimal. From this point it seems it's truly back to preference. Related: stackoverflow. Using a 0 prefix for octal has caused so very many problems over the years.

Notably in countries like the UK where telephone numbers start with a 0. Javascript and many other languages would parse these as octal, mangling the number before storing. To add to the fun, one popular database product would silently switch back to decimal parsing if the number contained an 8 or 9. Most of the hardware, software, and documentation of the time fit octal much better.

BCPL was first implemented on a 36 bit IBM , with an instruction format split into two 3 bit parts and 2 15 bit parts; 6 bit characters; and documentation in octal. B's early implementations were on a PDP-7 18 bit and a Honeywell GE 36 bit, but with 18 bit addressing, and support for 6 and 9 bit bytes. Show 3 more comments.

Note: I don't know the correct answer, but the below is just my personal speculation! Hex or a variable or type named FF00h? AshleysBrain AshleysBrain I imagine they could have used a leading 0 AND trailing h to denote hex. The trailing h probably would have been confused with the type specifier suffix, e. This argument implies that the use of a leading zero to denote octal numbers predates the use of the hexadecimal "0x" prefix.

Is this true? Wouldn't they have both been invented at the same time? BCPL is really work a look with odd 4-byte aligned pointers that you had to multiply by 4 to get the real address So far I do not see the point you want to make.

Also, the leading bold 8 was implementation specific. I wrote a lot of assembly language for that machine, data acquisition stuff for plasma fusion and astronomy, using octal.

I think the original motivation was to write operating systems as well as CPL compliers. Its simplicity was that it was completely typeless, so anything was possible. Its basic problem was that it assumed that the unit of addressing was 1, which works fine on some machines but not on others. Strachey] Programming language had good ideas but wsas too complex and ran out of impetus. I looked at the compiler but can't remember anything about it.

Show 11 more comments. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast Explaining the semiconductor shortage, and how it might end. Does ES6 make JavaScript frameworks obsolete? Featured on Meta.

Now live: A fully responsive profile. Linked