The symbol , known in
Unicode
Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...
as hyphen-minus, is the form of
hyphen most commonly used in digital
document
A document is a writing, written, drawing, drawn, presented, or memorialized representation of thought, often the manifestation of nonfiction, non-fictional, as well as fictional, content. The word originates from the Latin ', which denotes ...
s. On most keyboards, it is the only character that resembles a
minus sign or a
dash
The dash is a punctuation mark consisting of a long horizontal line. It is similar in appearance to the hyphen but is longer and sometimes higher from the baseline. The most common versions are the endash , generally longer than the hyphen ...
, so it is also used for these. The name ''hyphen-minus'' derives from the original
ASCII standard, where it was called ''hyphen (minus)''. The character is referred to as a ''hyphen'', a ''minus sign'', or a ''dash'' according to the context where it is being used.
Description
In early
typewriter
A typewriter is a Machine, mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of Button (control), keys, and each one causes a different single character to be produced on paper by striking an i ...
s and
character encodings, a single key/code was almost always used for hyphen, minus, various dashes, and strikethrough, since they all have a similar appearance. The current
Unicode Standard specifies distinct characters for several different
dash
The dash is a punctuation mark consisting of a long horizontal line. It is similar in appearance to the hyphen but is longer and sometimes higher from the baseline. The most common versions are the endash , generally longer than the hyphen ...
es, an unambiguous
minus sign (sometimes called the ''Unicode minus'') at
code point
A code point, codepoint or code position is a particular position in a Table (database), table, where the position has been assigned a meaning. The table may be one dimensional (a column), two dimensional (like cells in a spreadsheet), three dime ...
U+2212, an unambiguous
hyphen (sometimes called the ''Unicode hyphen'') at U+2010, the hyphen-minus at U+002D and a
variety of other hyphen symbols for various uses. When a hyphen is called for, the hyphen-minus is a common choice as it is well known, easy to enter on
keyboards, and still the only form recognized by many data formats and computer languages. Though the Unicode Standard states that the U+2010 hyphen is "preferred" over the hyphen-minus, the standard itself uses the hyphen-minus as its hyphen character.
In most modern
computer fonts, the hyphen-minus is either identical or very similar to the Unicode hyphen.
In mathematical texts that include the plus sign, the Unicode minus is preferred to the hyphen-minus, because its metrics match the plus sign in level and length.
Uses
Typing
This character is typed when a hyphen or a minus sign is wanted. Based on old typewriter conventions, it is common to use a pair to represent an
em dash , and to put spaces around it to represent a
spaced en dash ; this practice is deprecated in professional
typography
Typography is the art and technique of Typesetting, arranging type to make written language legibility, legible, readability, readable and beauty, appealing when displayed. The arrangement of type involves selecting typefaces, Point (typogra ...
. Some
word processors
automatically convert these to the correct dash. The character can also be typed multiple times to simulate a horizontal line (though in most cases, repeated entry of the
underscore will produce a solid line). Alternating the hyphen-minus with spaces produces a "dashed" line, often to indicate where paper is to be cut. On a typewriter, over-striking a section of text with this is used for
strikethrough.
Programming languages
Some
programming languages use the hyphen-minus for denoting subtraction and
additive inverse, often called ''negation''
in this context.
It is rarely used to indicate a range, due to ambiguity with subtraction. Generally, other characters, such as the Unicode are not recognized as an
operator.
In some programming languages (for example
MySQL
MySQL () is an Open-source software, open-source relational database management system (RDBMS). Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, and "SQL", the acronym for Structured Query Language. A rel ...
) (two hyphen-minus) mark the beginning of a
comment. It can be used to start the
signature block
A signature block (often abbreviated as signature, sig block, sig file, .sig, dot sig, siggy, or just sig) is a personalized block of text automatically appended at the bottom of an email message, Usenet article, or Internet forum, forum post.
E ...
in
Usenet
Usenet (), a portmanteau of User's Network, is a worldwide distributed discussion system available on computers. It was developed from the general-purpose UUCP, Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Elli ...
news system.
YAML uses (three hyphen-minuses) to end a section.
Command line
The hyphen-minus character is often used when specifying
command-line options, a convention popularized by
Unix. Examples of the "short" form are
-R or . A user can specify both by using
-Rq. Some implementations allow two hyphen-minuses to specify "long" option names as or . These are easier to understand when reading commands (some software does not care about the number of hyphen-minuses, and either does not allow combinations of single-letter options, or requires the user to rearrange them, so they do not match a long option). A double hyphen-minus by itself (followed by a space) indicates that there are no more options, which is useful when one needs to specify a filename that starts with a hyphen-minus. An option of just a hyphen-minus (followed by a space) may be recognized
in lieu of a filename and indicates that
stdin is to be read.
output
is used to denote deleted lines in
diff output in the or the .
Encoding
The glyph has a
code point
A code point, codepoint or code position is a particular position in a Table (database), table, where the position has been assigned a meaning. The table may be one dimensional (a column), two dimensional (like cells in a spreadsheet), three dime ...
in
Unicode
Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...
as . It is also in
ASCII with the same value.
See also
*
-- (disambiguation)
*
Dash
The dash is a punctuation mark consisting of a long horizontal line. It is similar in appearance to the hyphen but is longer and sometimes higher from the baseline. The most common versions are the endash , generally longer than the hyphen ...
(—)
*
Box-drawing characters including (U+2500), useful for drawing horizontal lines
*
Hyphen
*
Soft hyphen
Explanatory notes
References
External links
*
{{DEFAULTSORT:Hyphen-Minus
Punctuation
Typographical symbols