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The terms foobar (/ˈfuːbɑːr/), fubar, or foo, bar, baz and qux (alternatively, quux) are sometimes used as placeholder names (also referred to as metasyntactic variables) in computer programming or computer-related documentation. They have been used to name entities such as variables, functions, and commands whose purpose is unimportant and serve only to demonstrate a concept. The words themselves have no meaning in this usage. Foobar is sometimes used alone; foo, bar, and baz are sometimes used, when multiple entities are needed.

The usage in computer programming examples and pseudocode varies; in certain circles, it is used extensively, but many prefer descriptive names, while others prefer to use single letters. Eric S. Raymond has called it an "important hackerism" alongside kludge and cruft.

History and etymology

The word foo originated as a nonsense word from the 1930s, the military term FUBAR emerged in the 1940s, and the use of foo in a programming context is generally credited to the Tech Model Railroad Club (TMRC) of M.I.T. from circa 1960. However, the precise relationship of these terms is not known with certainty, and several anecdotal theories have been advanced to identify them.

The etymology of foo is explored in the Internet Engineering Task Force (IETF) RFC 3092, which gives the earliest documented use as being in the 1930s comic Smokey Stover by Bill Holman, where it is used as a nonsense word. Holman states that he used the word due to having seen it on bottom of a jade Chinese figurine in Chinatown, San Francisco, meaning "good luck". This is presumably as a transliteration of the fu character (fú, 福), which is a common character for fortune, and figurines of the trio of eponymous male "star gods" Fú, Lù, Shòu are common in Chinese communities, as illustrated at right; compare Fu Manchu, fictional character popular in the 1930s. Smokey Stover ran 1935–73, and continued to feature foo prominently, as on the front of the "foomobile" illustrated in the cover at right. The word foo became very popular in the 1930s, and also appeared in other cartoons including the Looney Tunes cartoons of Bob Clampett such as The Daffy Doc and Porky in Wackyland (both 1938, with Daffy Duck and Porky Pig), and in other comic strips such as Pogo.

From there, the Foo migrated into military slang, merged with "FU" of the FUBAR. The term foo fighter was used by Allied aircraft pilots in World War II to describe various UFOs or mysterious aerial phenomena.

The first known use of the terms in print in a programming context appears in a 1965 edition of MIT's "Tech Engineering News". Foobar may have come about as a result of the pre-existing "Foo" being conjoined with with "bar" an addition borrowed from the military's FUBAR. The use of foo in hacker and eventually in programming context may have begun in MIT's Tech Model Railroad Club (TMRC). In the complex model system, there were scram switches located at numerous places around the room that could be thrown if something undesirable was about to occur, such as a train going full-bore at an obstruction. Another feature of the system was a digital clock on the dispatch board. When someone hit a scram switch the clock stopped and the display was replaced with the word "FOO"; at TMRC the scram switches are therefore called "Foo switches". Because of this, an entry in the 1959 Dictionary of the TMRC Language went something like this: "FOO: The first syllable of the misquoted sacred chant phrase 'foo mane padme hum.' Our first obligation is to keep the foo counters turning." One book describing the MIT train room describes two buttons by the door: labelled foo and bar. These were general purpose buttons and were often re-purposed for whatever fun idea the MIT hackers had at the time, hence the adoption of foo and bar as general purpose variable names. An entry in the "Abridged Dictionary of the TMRC Language" states "Multiflush: stop-all-trains-button. Next best thing to the red door button. Also called FOO. Displays "FOO" on the clock when used."

The term foobar was propagated through computer science circles in the 1960s and early 1970s by system manuals from Digital Equipment Corporation. Foobar was also used as a variable name in the Fortran code of Colossal Cave Adventure (1977 Crowther and Woods version). The variable FOOBAR was used to contain the player's progress in saying the magic phrase "Fee Fie Foe Foo".

Usage in code

The terms are very often used in programming examples, much like the Hello World program is commonly used as an introduction. For example, foo and bar might be used to illustrate a simple string concatenation:

/* C code */
#include <stdio.h>
int main()
{
   char *foo = "Hello";
   char *bar = "World!";
   fprintf(stdout, "%s %s\n", foo, bar);
   return 0;
}

/* PHP code */
$foo = 'Hello';
$bar = array($foo, ' ', 'world', '!');
echo implode('', $bar);

/* Java code */
public class Foobar
{
  public static void main(String args)
  {
    String foo = "Hello";
    String bar = "World!";
    System.out.println(foo + " " + bar);
  }
}

# Ruby code
foo = "Hello"
bar = "World!"
puts foo + " " + bar

/* C# code */
using System;
namespace FooBar{
    internal sealed class Foobar{
        private static void Main(String args){
            String foo = "Hello";
            String bar = "world!!.";
            Console.WriteLine("{0} {1}", foo, bar);
            Console.ReadKey();
        }
    }
}

/* Visual Basic 2010 code */
Dim foo As String = "Hello"
Dim bar As String() = {foo, "World"}
Console.Writeline(String.Format("{0} {1}", bar(0), bar(1))
Console.ReadKey

Additional examples of the use of foo and bar in code are given in the entry on metasyntactic variables.

Usage in culture

$foo is the name of a Perl programming magazine, and Foo Camp is an annual hacker convention.

During the United States v. Microsoft trial, some evidence was presented that Microsoft had tried to use the Web Services Interoperability organization as a means to stifle competition, including e-mails in which top executives including Bill Gates referred to the WS-I using the codename "foo".

These terms gave the name to foobar2000, an audio player independently developed using C++, as its author was more focused on producing a functional program than on aesthetics.

References

1. ^ D. Eastlake III; et al. (2001). "Etymology of "Foo"". Internet Engineering Task Force. Retrieved 2007-11-05. {{cite web}}: Explicit use of et al. in: |author= (help)
2. Eric S. Raymond (1996). The New Hacker's Dictionary. MIT Press. ISBN 0-262-68092-0.
3. “foo”, The Jargon File
4. "The History of Bill Holman", Smokey-Stover.com, Smokey Stover LLC – article by nephew of Bill Holman
5. "Warner Brothers Cartoon Companion"
6. Tech Engineering News, Volume 47. Massachusetts Institute of Technology. 1965. p. 63. Further, it is possible to search for an effective address; e.g., if an instruction such as "add 1 foo" were used, specifying indirect addressing thru location "foo", and location "foo" contained the address of location "foobar", than an effective word search for "foobar" would find location "foo" and the location containing the "add" instruction as well.
7. "Computer Dictionary Online"., computer-dictionary-online.org
8. "Abridged Dictionary of the TMRC Language". MIT.
9. Foo-magazin.de Template:De icon
10. Microsoft ploy to block Sun exposed, news.com

External links

• RFC3092 Etymology of "Foo", tools.ietf.org
• The Free Online Dictionary of Computing entry on "foo", foldoc.org
• The Jargon File entry on "foobar", catb.org
• RFC 1639 – FTP Operation Over Big Address Records (FOOBAR)

• Placeholder names
• Variable (computer programming)