<
Less-than sign
In UnicodeU+003C < LESS-THAN SIGN (&lt;, &LT;)
Different from
Different fromU+2329 LEFT-POINTING ANGLE BRACKET
Related
See alsoU+003E > GREATER-THAN SIGN
U+2264 LESS-THAN OR EQUAL TO

U+2A7D LESS-THAN OR SLANTED EQUAL TO used e.g. in Poland

U+226E NOT LESS-THAN
U+226A MUCH LESS-THAN

The less-than sign is a mathematical symbol that denotes an inequality between two values. The widely adopted form of two equal-length strokes connecting in an acute angle at 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 include 12 < 1 and −2 < 0.

Since the development of computer programming languages, the less-than sign and the greater-than sign have been repurposed for a range of uses and operations.

Computing

The less-than sign, <, is an original ASCII character (hex 3C, decimal 60).

Programming

In BASIC, Lisp-family languages, and C-family languages (including Java and C++), comparison operator < means "less than".

In Coldfusion, operator .lt. means "less than".

In Fortran, operator .LT. means "less than"; later versions allow <.

Shell scripts

In Bourne shell (and many other shells), operator -lt means "less than". Less-than sign is used to redirect input from a file. Less-than plus ampersand (<&) is used to redirect from a file descriptor.

Double less-than sign

The double less-than sign, <<, may be used for an approximation of the much-less-than sign () or of the opening guillemet («). ASCII does not encode either of these signs, though they are both included in Unicode.

In Bash, Perl, and Ruby, operator <<EOF (where "EOF" is an arbitrary string, but commonly "EOF" denoting "end of file") is used to denote the beginning of a here document.

In C and C++, operator << represents a binary left shift.

In the C++ Standard Library, operator <<, when applied on an output stream, acts as insertion operator and performs an output operation on the stream.

In Ruby, operator << acts as append operator when used between an array and the value to be appended.

In XPath the << operator returns true if the left operand precedes the right operand in document order; otherwise it returns false.[1]

Triple less-than sign

In PHP, operator <<<OUTPUT is used to denote the beginning of a heredoc statement (where OUTPUT is an arbitrary named variable.)

In Bash, <<<word is used as a "here string", where word is expanded and supplied to the command on its standard input, similar to a heredoc.

Less-than sign with equals sign

The less-than sign with the equals sign, <=, may be used for an approximation of the less-than-or-equal-to sign, . ASCII does not have a less-than-or-equal-to sign, but Unicode defines it at code point U+2264.

In BASIC, Lisp-family languages, and C-family languages (including Java and C++), operator <= means "less than or equal to". In Sinclair BASIC it is encoded as a single-byte code point token.

In Prolog, =< means "less than or equal to" (as distinct from the arrow <=).

In Fortran, operators .LE. and <= both mean "less than or equal to".

In Bourne shell and Windows PowerShell, the operator -le means "less than or equal to".

Less-than sign with hyphen-minus

In the R programming language, the less-than sign is used in conjunction with a hyphen-minus to create an arrow (<-), this can be used as the left assignment operator.

Spaceship operator

Less-than sign is used in the spaceship operator.

HTML

In HTML (and SGML and XML), the less-than sign is used at the beginning of tags. The less-than sign may be included with &lt;. The less-than-or-equal-to sign, , may be included with &le;.

Unicode

Unicode provides various Less Than Symbol:[2]

SymbolNameCode Point
Apl Functional Symbol Quad Less ThanU+2343
Circled Less ThanU+29C0
Double Right Arc Less Than BracketU+2996
Equal To Or Less ThanU+22DC
Left Arc Less Than BracketU+2993
Leftwards Arrow Through Less ThanU+2977
Less Than Above Leftwards ArrowU+2976
Less Than But Not Equal ToU+2268
Less Than But Not Equivalent ToU+22E6
Less Than Or Equal ToU+2264
Less Than Or Equivalent ToU+2272
Less Than Over Equal ToU+2266
<Less Than SignU+003C
Less Than With Circle InsideU+2A79
Less Than With DotU+22D6
Much Less ThanU+226A
Neither Less Than Nor Equal ToU+2270
Neither Less Than Nor Equivalent ToU+2274
Not Less ThanU+226E
Very Much Less ThanU+22D8

The less-than sign may be seen for an approximation of the opening angle bracket, . True angle bracket characters, as required in linguistics notation, are expected in formal texts.

Mathematics

In 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.

See also

References

  1. "XML Path Language (XPath) 2.0 (Second Edition)". www.w3.org. W3C. 14 December 2010. Archived from the original on 7 October 2022. Retrieved 29 October 2019.
  2. "Less than symbol". Archived from the original on 2023-05-16. Retrieved 2023-06-06.
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