Less-than sign
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 1⁄2 < 1 and −2 < 0.
| < | |
|---|---|
Less-than sign | |
| In Unicode | 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 TO used e.g. in Poland U+226A ≪ MUCH LESS-THAN |
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).
The less-than sign may be used for an approximation of the opening angle bracket, ⟨. ASCII does not have angle brackets but are standard in Unicode (U+2329 〈 LEFT-POINTING ANGLE BRACKET). The latter is expected in formal texts.
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.
Unicode
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 |
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.
References
- "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.
- "Less than symbol". Archived from the original on 2023-05-16. Retrieved 2023-06-06.