Editing Hexadecimal (section)

====Distinguishing from decimal====
In contexts where the [[radix|base]] is not clear, hexadecimal numbers can be ambiguous and confused with numbers expressed in other bases. There are several conventions for expressing values unambiguously. A numerical subscript (itself written in decimal) can give the base explicitly: 159<sub>10</sub> is decimal 159; 159<sub>16</sub> is hexadecimal 159, which equals 345<sub>10</sub>. Some authors prefer a text subscript, such as 159<sub>decimal</sub> and 159<sub>hex</sub>, or 159<sub>d</sub> and 159<sub>h</sub>.

[[Donald Knuth]] introduced the use of a particular typeface to represent a particular radix in his book ''The TeXbook''.<ref>{{Cite book |last=Knuth |first=Donald Ervin |url=https://www.worldcat.org/oclc/12973034 |title=The TeXbook |date=1986 |others=Duane Bibby |isbn=0-201-13447-0 |location=Reading, Mass. |oclc=12973034 |access-date=2022-03-15  |archive-date=2022-01-16  |archive-url=https://web.archive.org/web/20220116012119/http://www.worldcat.org/oclc/12973034 |url-status=live }}</ref> Hexadecimal representations are written there in a [[Monospaced font|typewriter typeface]]: {{mono|5A3}}, {{mono|C1F27ED}}

In linear text systems, such as those used in most computer programming environments, a variety of methods have arisen:<!--
 * * * These are ordered from most to least likely to be encountered by lay people
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* {{anchor|_nix}}Although best known from the [[C (programming language)|C programming language]] (and the many languages influenced by C), the prefix <code>0x</code> to indicate a hex constant may have had origins in the [[IBM Stretch]] systems. It is derived from the <code>0</code> prefix already in use for [[octal]] constants. Byte values can be expressed in hexadecimal with the prefix <code>\x</code> followed by two hex digits: <code>'\x1B'</code> represents the [[Escape character|Esc]] control character; <code>"\x1B[0m\x1B[25;1H"</code> is a string containing 11 characters with two embedded Esc characters.<ref>The string <code>"\x1B[0m\x1B[25;1H"</code> specifies the character sequence {{mono|Esc [ 0 m Esc [ 2 5; 1 H}}. These are the escape sequences used on an [[ANSI escape code|ANSI terminal]] that reset the character set and color, and then move the cursor to line 25.</ref> To output an integer as hexadecimal with the [[printf]] function family, the format conversion code <code>%X</code> or <code>%x</code> is used.
* In [[XML]] and [[XHTML]], characters can be expressed as hexadecimal [[numeric character reference]]s using the notation <code>&amp;#x''code'';</code>, for instance <code>&amp;#x0054;</code> represents the character U+0054 (the uppercase letter "T"). If there is no {{code|x}} the number is decimal (thus <code>&amp;#0084;</code> is the same character).<ref>{{cite web|url=https://www.unicode.org/charts/PDF/U2000.pdf|title=The Unicode Standard, Version 7|website=Unicode|access-date=28 October 2018|archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303175510/http://www.unicode.org/charts/PDF/U2000.pdf|url-status=live}}</ref>
* {{anchor|Intel}}In Intel-derived [[assembly language]]s and Modula-2,<ref>{{cite web |title=Modula-2 – Vocabulary and representation |url=http://modula2.org/reference/vocabulary.php |website=Modula −2 |access-date=1 November 2015 |archive-date=2015-12-13  |archive-url=https://web.archive.org/web/20151213053318/http://www.modula2.org/reference/vocabulary.php |url-status=live }}</ref> hexadecimal is denoted with a suffixed {{mono|H}} or {{mono|h}}: <code>FFh</code> or <code>05A3H</code>. Some implementations require a leading zero when the first hexadecimal digit character is not a decimal digit, so one would write <code>0FFh</code> instead of <code>FFh</code>. Some other implementations (such as NASM) allow C-style numbers (<code>0x42</code>).
* {{anchor|Motorola}}Other assembly languages ([[MOS Technology 6502|6502]], [[Motorola]]), [[Pascal (programming language)|Pascal]], [[Delphi (programming language)|Delphi]], some versions of [[BASIC]] ([[Commodore BASIC|Commodore]]), [[GameMaker Studio|GameMaker Language]], [[Godot (game engine)|Godot]] and [[Forth (programming language)|Forth]] use <code>$</code> as a prefix: <code>$5A3</code>, <code>$C1F27ED</code>.
* Some assembly languages (Microchip) use the notation <code>H'ABCD'</code> (for ABCD<sub>16</sub>). Similarly, [[Fortran 95 language features|Fortran 95]] uses Z'ABCD'.
* [[Ada (programming language)|Ada]] and [[VHDL]] enclose hexadecimal numerals in based "numeric quotes": <code>16#5A3#</code>, <code>16#C1F27ED#</code>. For bit vector constants [[VHDL]] uses the notation <code>x"5A3"</code>, <code>x"C1F27ED"</code>.<ref>{{cite web |url=https://www.fpgatutorial.com/vhdl-types-and-conversions#vhdl-assign-data |title=An Introduction to VHDL Data Types |website=FPGA Tutorial |date=10 May 2020 |access-date=2020-08-21 |archive-date=2020-08-23  |archive-url=https://web.archive.org/web/20200823094252/https://www.fpgatutorial.com/vhdl-types-and-conversions/#vhdl-assign-data |url-status=live }}</ref>
* [[Verilog]] represents hexadecimal constants in the form <code>8'hFF</code>, where 8 is the number of bits in the value and FF is the hexadecimal constant.
* The [[Icon (programming language)|Icon]] and [[Smalltalk]] languages use the prefix <code>16r</code>: <code>16r5A3</code>
* [[PostScript]] and the [[Bourne shell]] and its derivatives denote hex with prefix <code>16#</code>: <code>16#5A3</code>, <code>16#C1F27ED</code>.
* [[Common Lisp]] uses the prefixes <code>#x</code> and <code>#16r</code>. Setting the variables *read-base*<ref>{{cite web |title=*read-base* variable in Common Lisp |url=http://www.lispworks.com/documentation/HyperSpec/Body/v_rd_bas.htm |website=CLHS |access-date=2015-01-10  |archive-date=2016-02-03  |archive-url=https://web.archive.org/web/20160203221612/http://www.lispworks.com/documentation/HyperSpec/Body/v_rd_bas.htm |url-status=live }}</ref> and *print-base*<ref>{{cite web |title=*print-base* variable in Common Lisp |url=http://www.lispworks.com/documentation/HyperSpec/Body/v_pr_bas.htm#STprint-baseST |website=CLHS |access-date=2015-01-10  |archive-date=2014-12-26  |archive-url=https://web.archive.org/web/20141226172420/http://www.lispworks.com/documentation/HyperSpec/Body/v_pr_bas.htm#STprint-baseST |url-status=live }}</ref> to 16 can also be used to switch the reader and printer of a Common Lisp system to Hexadecimal number representation for reading and printing numbers. Thus Hexadecimal numbers can be represented without the #x or #16r prefix code, when the input or output base has been changed to 16.
* [[MSX BASIC]],<ref>[http://www.atarimagazines.com/compute/issue56/107_1_MSX_IS_COMING.php MSX is Coming — Part 2: Inside MSX] {{Webarchive|url=https://web.archive.org/web/20101124111223/http://www.atarimagazines.com/compute/issue56/107_1_MSX_IS_COMING.php |date=2010-11-24  }} [[Compute!]], issue 56, January 1985, p. 52</ref> [[QuickBASIC]], [[FreeBASIC]] and [[Visual Basic]] prefix hexadecimal numbers with <code>&amp;H</code>: <code>&amp;H5A3</code>
* [[BBC BASIC]] and [[Locomotive BASIC]] use <code>&amp;</code> for hex.<ref>BBC BASIC programs are not fully portable to [[Microsoft BASIC]] (without modification) since the latter takes <code>&amp;</code> to prefix [[octal]] values. (Microsoft BASIC primarily uses <code>&amp;O</code> to prefix octal, and it uses <code>&amp;H</code> to prefix hexadecimal, but the ampersand alone yields a default interpretation as an octal prefix.</ref>
* [[TI-89]] and 92 series uses a <code>0h</code> prefix: <code>0h5A3</code>, <code>0hC1F27ED</code>
* [[ALGOL 68]] uses the prefix <code>16r</code> to denote hexadecimal numbers: <code>16r5a3</code>, <code>16rC1F27ED</code>. Binary, quaternary (base-4), and octal numbers can be specified similarly.
* The most common format for hexadecimal on IBM mainframes ([[zSeries]]) and midrange computers ([[IBM i]]) running the traditional OS's ([[z/OS|zOS]], [[VSE (operating system)|zVSE]], [[z/VM|zVM]], [[Transaction Processing Facility|TPF]], [[IBM i]]) is <code>X'5A3'</code> or <code>X'C1F27ED'</code>, and is used in Assembler, [[PL/I]], [[COBOL]], [[Job Control Language|JCL]], scripts, commands and other places. This format was common on other (and now obsolete) IBM systems as well.  Occasionally quotation marks were used instead of apostrophes.