This articleneeds additional citations forverification.(June 2019) |
Theless-than signis a mathematical symbol that denotes aninequalitybetween two values. The widely adopted form of two equal-length strokes connecting in anacute angleat the left,<,has been found in documents dated as far back as the 1560s. In mathematical writing, the less-than sign is typically placed between two values being compared and signifies that the first number is less than the second number. Examples of typical usage include1⁄2< 1and−2 < 0.
< | |
---|---|
Less-than sign | |
InUnicode | U+003C<LESS-THAN SIGN(<, <) |
Different from | |
Different from | U+2329〈LEFT-POINTING ANGLE BRACKET |
Related | |
See also | U+003E>GREATER-THAN SIGN U+2264≤LESS-THAN OR EQUAL TO U+2A7D⩽LESS-THAN OR SLANTED EQUAL TOused e.g. in Poland U+226A≪MUCH LESS-THAN |
Since the development of computerprogramming languages,the less-than sign and thegreater-than signhave been repurposed for a range of uses and operations.
Computing
editTheless-than sign,<,is an originalASCIIcharacter (hex 3C, decimal 60).
Programming
editInBASIC,Lisp-family languages, andC-family languages (includingJavaandC++),comparison operator<
means "less than".
InColdfusion,operator.lt.
means "less than".
InFortran,operator.LT.
means "less than"; later versions allow<
.
Shell scripts
editInBourne shell(and many other shells), operator-lt
means "less than". Less-than sign is used toredirectinput from a file. Less-than plus ampersand (<&
) is used to redirect from afile descriptor.
Double less-than sign
editThedouble less-than sign,<<,may be used for an approximation of themuch-less-than sign(≪) or of the openingguillemet(«). ASCII does not encode either of these signs, though they are both included inUnicode.
InBash,Perl,andRuby,operator<<EOF
(where "EOF" is an arbitrary string, but commonly "EOF" denoting "end of file" ) is used to denote the beginning of ahere document.
InCandC++,operator<<
represents abinary left shift.
In theC++ Standard Library,operator<<
,when applied on an output stream, acts asinsertion operatorand performs an output operation on the stream.
InRuby,operator<<
acts asappend operatorwhen used between an array and the value to be appended.
InXPaththe<<
operator returns true if the left operand precedes the right operand in document order; otherwise it returns false.[1]
Triple less-than sign
editInPHP,operator<<<OUTPUT
is used to denote the beginning of aheredocstatement (whereOUTPUT
is an arbitrary named variable.)
In Bash,<<<word
is used as a "here string", whereword
is expanded and supplied to the command on its standard input, similar to a heredoc.
Less-than sign with equals sign
editThe less-than sign with the equals sign,<=
,may be used for an approximation of theless-than-or-equal-to sign,≤.ASCII does not have a less-than-or-equal-to sign, butUnicodedefines it at code point U+2264.
InBASIC,Lisp-family languages, andC-family languages (includingJavaandC++), operator<=
means "less than or equal to". InSinclair BASICit is encoded as a single-byte code point token.
InProlog,=<
means "less than or equal to" (as distinct from the arrow<=
).
InFortran,operators.LE.
and<=
both mean "less than or equal to".
InBourne shellandWindows PowerShell,the operator-le
means "less than or equal to".
Less-than sign with hyphen-minus
editIn theR programming language,the less-than sign is used in conjunction with ahyphen-minusto create an arrow (<-
), this can be used as the left assignment operator.
Spaceship operator
editLess-than sign is used in thespaceship operator.
HTML
editInHTML(andSGMLandXML), the less-than sign is used at the beginning of tags. The less-than sign may be included with<
.The less-than-or-equal-to sign,≤,may be included with≤
.
Unicode
editUnicodeprovides various Less Than Symbol:[2]
Symbol | Name | Code Point |
---|---|---|
⍃ | Apl Functional Symbol Quad Less Than | U+2343 |
⧀ | Circled Less Than | U+29C0 |
⦖ | Double Right Arc Less Than Bracket | U+2996 |
< | Fullwidth less than | U+FF1C |
⋜ | Equal To Or Less Than | U+22DC |
⦓ | Left Arc Less Than Bracket | U+2993 |
⥷ | Leftwards Arrow Through Less Than | U+2977 |
⥶ | Less Than Above Leftwards Arrow | U+2976 |
≨ | Less Than But Not Equal To | U+2268 |
⋦ | Less Than But Not Equivalent To | U+22E6 |
≤ | Less Than Or Equal To | U+2264 |
≲ | Less Than Or Equivalent To | U+2272 |
≦ | Less Than Over Equal To | U+2266 |
< | Less Than Sign | U+003C |
⩹ | Less Than With Circle Inside | U+2A79 |
⋖ | Less Than With Dot | U+22D6 |
≪ | Much Less Than | U+226A |
≰ | Neither Less Than Nor Equal To | U+2270 |
≴ | Neither Less Than Nor Equivalent To | U+2274 |
≮ | Not Less Than | U+226E |
﹤ | Small Less Than Sign | U+FE64 |
⋘ | Very Much Less Than | U+22D8 |
The less-than sign may be seen for an approximation of the openingangle bracket,⟨.True angle bracket characters, as required inlinguistics notation,are expected in formal texts.
Mathematics
editIn an inequality, the less-than sign and greater-than sign always "point" to the smaller number. Put another way, the "jaws" (the wider section of the symbol) always direct to the larger number.
The less-than-sign is sometimes used to represent atotal order,partial orderorpreorder.However, the symbolis often used when it would be confusing or not convenient to use<.In mathematical writing usingLaTeX,theTeXcommand is\prec
.The Unicodecode pointisU+227A≺PRECEDES.
See also
editReferences
edit- ^"XML Path Language (XPath) 2.0 (Second Edition)".w3.org.W3C. 14 December 2010. Archived fromthe originalon 7 October 2022.Retrieved29 October2019.
- ^"Less than symbol".Archivedfrom the original on 2023-05-16.Retrieved2023-06-06.