7.1.2 @code{sample-code}

Use the @code command to indicate text that is a piece of a program and which consists of entire syntactic tokens. Enclose the text in braces.

Thus, you should use @code for an expression in a program, for the name of a variable or function used in a program, or for a keyword in a programming language.

Use @code for command names in languages that resemble programming languages, such as Texinfo. For example, @code and @samp are produced by writing ‘@code{@@code}’ and ‘@code{@@samp}’ in the Texinfo source, respectively.

It is incorrect to alter the case of a word inside a @code command when it appears at the beginning of a sentence. Most computer languages are case sensitive. In C, for example, Printf is different from the identifier printf, and most likely is a misspelling of it. Even in languages which are not case sensitive, it is confusing to a human reader to see identifiers spelled in different ways. Pick one spelling and always use that. If you do not want to start a sentence with a command name written all in lowercase, you should rearrange the sentence.

In the Info output, @code results in single quotation marks around the text. In other formats, @code argument is typeset in a typewriter (monospace) font. For example,

The function returns @code{nil}.

produces this:

The function returns nil.

Here are some cases for which it is preferable not to use @code:

• For shell command names, such as ls (use @command).
• For environment variables, such as TEXINPUTS (use @env).
• For shell options, such as ‘-c’, when such options stand alone (use @option).
• An entire shell command often looks better if written using @samp rather than @code. In this case, the rule is to choose the more pleasing format.
• For a string of characters shorter than a syntactic token. For example, if you are writing about ‘goto-ch’, which is just a part of the name for the goto-char Emacs Lisp function, you should use @samp.
• In general, when writing about the characters used in a token; for example, do not use @code when you are explaining what letters or printable symbols can be used in the names of functions. (Use @samp.) Also, you should not use @code to mark text that is considered input to programs unless the input is written in a language that is like a programming language. For example, you should not use @code for the keystroke commands of GNU Emacs (use @kbd instead) although you may use @code for the names of the Emacs Lisp functions that the keystroke commands invoke.

By default, TeX will consider breaking lines at ‘-’ and ‘_’ characters within @code and related commands. This can be controlled with @allowcodebreaks (see @allowcodebreaks). The HTML output attempts to respect this for ‘-’, but ultimately it is up to the browser’s behavior. For Info, it seems better never to make such breaks.

For Info, the quotes are omitted in the output of the @code command and related commands (e.g., @kbd, @command), in typewriter-like contexts such as the @example environment (see @example) and @code itself, etc.

To control which quoting characters are implicitly inserted by Texinfo processors in the output of ‘@code’, etc., see the OPEN_QUOTE_SYMBOL and CLOSE_QUOTE_SYMBOL customization variables (see Other Customization Variables). This is separate from how actual quotation characters in the input document are handled (see Inserting Quote Characters).