Less-than sign
Mathematical symbol for "less than"
From Wikipedia, the free encyclopedia
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 < 4 and â2 < 0.
| < | |
|---|---|
Less-than sign | |
| In Unicode | U+003C < LESS-THAN SIGN (<, <) |
| Related | |
| See also | similar symbols listed below |
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 (âª) 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, â¤. 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
The 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 <. The less-than-or-equal-to sign, â¤, may be included with ≤.
Unicode
Unicode provides various less than symbols:[2]
| Symbol | Unicode name | Code Point |
|---|---|---|
| < | Less-Than Sign | U+003C |
| ⤠| Less-Than Or Equal To | U+2264 |
| ⦠| Less-Than Over Equal To | U+2266 |
| ⨠| Less-Than But Not Equal To | U+2268 |
| ⪠| Much Less-Than | U+226A |
| â® | Not Less Than | U+226E |
| â° | Neither Less-Than Nor Equal To | U+2270 |
| â² | Less-Than Or Equivalent To | U+2272 |
| â´ | Neither Less-Than Nor Equivalent To | U+2274 |
| â | Less-Than With Dot | U+22D6 |
| â | Very Much Less-Than | U+22D8 |
| â | Equal To Or Less-Than | U+22DC |
| ⦠| Less-Than But Not Equivalent To | U+22E6 |
| â | Apl Functional Symbol Quad Less-Than | U+2343 |
| ⥶ | Less-Than Above Leftwards Arrow | U+2976 |
| ⥷ | Leftwards Arrow Through Less-Than | U+2977 |
| ⦠| Left Arc Less-Than Bracket | U+2993 |
| ⦠| Double Right Arc Less-Than Bracket | U+2996 |
| ⧠| Circled Less-Than | U+29C0 |
| ⩹ | Less-Than With Circle Inside | U+2A79 |
| â©» | Less-Than With Question Mark Above | U+2A7B |
| ⩽ | Less-Than Or Slanted Equal To | U+2A7D |
| â©¿ | Less-Than Or Slanted Equal To With Dot Inside | U+2A7F |
| ⪠| Less-Than Or Slanted Equal To With Dot Above | U+2A81 |
| ⪠| Less-Than Or Slanted Equal To With Dot Above Right | U+2A83 |
| ⪠| Less-Than Or Approximate | U+2A85 |
| ⪠| Less-Than And Single-Line Not Equal To | U+2A87 |
| ⪠| Less-Than And Not Approximate | U+2A89 |
| ⪠| Less-Than Above Similar Or Equal | U+2A8D |
| ⪠| Slanted Equal Or Less-Than | U+2A95 |
| ⪠| Slanted Equal Or Less-Than With Dot Inside | U+2A97 |
| ⪠| Double-Line Equal To Or Less-Than | U+2A99 |
| ⪠| Double-Line Slanted Equal To Or Less-Than | U+2A9B |
| ⪠| Similar To Or Less-Than | U+2A9D |
| ⪠| Similar Above Less-Than Above Equals Sign | U+2A9F |
| ⪡ | Double Nested Less-Than | U+2AA1 |
| ⪣ | Double Nested Less-Than With Underbar | U+2AA3 |
| ⪦ | Less-Than Closed By Curve | U+2AA6 |
| ⪨ | Less-Than Closed By Curve Above Slanted Equal | U+2AA8 |
| â«· | Triple Nested Less-Than | U+2AF7 |
| ⫹ | Double-line Slanted Less-than Or Equal To | U+2AF9 |
| ﹤ | Small Less-Than Sign | U+FE64 |
| ï¼ | Fullwidth Less-Than | U+FF1C |
The less-than sign may be seen for an approximation of the opening angle bracket, â¨. 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.
The less-than-sign is sometimes used to represent a total order, partial order or preorder. However, the symbol is often used when it would be confusing or not convenient to use <. In mathematical writing using LaTeX, the TeX command is \prec. The Unicode code point is U+227A ⺠PRECEDES.
