Why 0x for hex

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. Improve this answer. 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? Why would there ever be one but not the other?

In x86 Intel assembly a hex literal must always be prefixed by 0 if they begin with a character. I remember it from inline asm in Pascal when I was young stackoverflow. Show 2 more comments. For binary it would be: 0b Hope I have helped in some way.

Good day! Zeus 7 7 silver badges 23 23 bronze badges. Binary can only be one digit. PeteBecker But then again, binary too is as well only a single digit. Every power of two needs in binary only a single digit Show 2 more comments.

Active Oldest Votes. Improve this answer. Raffzahn Raffzahn k 17 17 gold badges silver badges bronze badges. 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. The prefix 0x is used in code to indicate that the number is being written in hex. The hexadecimal format has a base of 16, which means that each digit can represent up to 16 different values.

We convert the number the same way as before. Knowing how to convert binary and hex to decimal is important, but the most useful number conversion is probably converting between hex and binary.

These two numbering systems actually work pretty well together. The numbering systems happen to be related such that a single hex digit represents exactly 4 binary digits, and so 2 hex digits can represent 8 bits or binary digits.

For example, to convert the hex number 0x1C to binary, we would find the corresponding binary value for 1 and C and combine them. So, 0x1C in binary is 0b If we wanted to figure out the hex value for a binary number we just go the other way. To find the hex representation of the binary number 0b There are many free tools available to help convert between these numbering systems, just google 'hex number conversion.

Just change the calculator to scientific mode and you can convert between number systems by typing a number then changing the format of the calculator! Please log in to save your answers. Need Help? Mountain Time: Shopping Cart 0 items. Product Menu.