Less-than sign

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<
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[edit]

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

Programming[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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[edit]

Less-than sign is used in the spaceship operator.

HTML[edit]

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[edit]

Unicode provides 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
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
Very Much Less Than U+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[edit]

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[edit]

References[edit]

  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.