Less-than sign

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 < 4 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

Less-than sign

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.

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

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 &lt;. The less-than-or-equal-to sign, ≤, may be included with &le;.

Unicode

Less-than sign

Unicode provides various less than symbols:

<table><thead><tr><th>Symbol</th><th>Unicode name</th><th>Code Point</th></tr></thead><tbody><tr><td><</td><td>LESS-THAN SIGN</td><td>U+003C</td></tr><tr><td>≤</td><td>LESS-THAN OR EQUAL TO</td><td>U+2264</td></tr><tr><td>≦</td><td>LESS-THAN OVER EQUAL TO</td><td>U+2266</td></tr><tr><td>≨</td><td>LESS-THAN BUT NOT EQUAL TO</td><td>U+2268</td></tr><tr><td>≪</td><td>MUCH LESS-THAN</td><td>U+226A</td></tr><tr><td>≮</td><td>NOT LESS THAN</td><td>U+226E</td></tr><tr><td>≰</td><td>NEITHER LESS-THAN NOR EQUAL TO</td><td>U+2270</td></tr><tr><td>≲</td><td>LESS-THAN OR EQUIVALENT TO</td><td>U+2272</td></tr><tr><td>≴</td><td>NEITHER LESS-THAN NOR EQUIVALENT TO</td><td>U+2274</td></tr><tr><td>⋖</td><td>LESS-THAN WITH DOT</td><td>U+22D6</td></tr><tr><td>⋘</td><td>VERY MUCH LESS-THAN</td><td>U+22D8</td></tr><tr><td>⋜</td><td>EQUAL TO OR LESS-THAN</td><td>U+22DC</td></tr><tr><td>⋦</td><td>LESS-THAN BUT NOT EQUIVALENT TO</td><td>U+22E6</td></tr><tr><td>⍃</td><td>APL FUNCTIONAL SYMBOL QUAD LESS-THAN</td><td>U+2343</td></tr><tr><td>⥶</td><td>LESS-THAN ABOVE LEFTWARDS ARROW</td><td>U+2976</td></tr><tr><td>⥷</td><td>LEFTWARDS ARROW THROUGH LESS-THAN</td><td>U+2977</td></tr><tr><td>⦓</td><td>LEFT ARC LESS-THAN BRACKET</td><td>U+2993</td></tr><tr><td>⦖</td><td>DOUBLE RIGHT ARC LESS-THAN BRACKET</td><td>U+2996</td></tr><tr><td>⧀</td><td>CIRCLED LESS-THAN</td><td>U+29C0</td></tr><tr><td>⩹</td><td>LESS-THAN WITH CIRCLE INSIDE</td><td>U+2A79</td></tr><tr><td>⩻</td><td>LESS-THAN WITH QUESTION MARK ABOVE</td><td>U+2A7B</td></tr><tr><td>⩽</td><td>LESS-THAN OR SLANTED EQUAL TO</td><td>U+2A7D</td></tr><tr><td>⩿</td><td>LESS-THAN OR SLANTED EQUAL TO WITH DOT INSIDE</td><td>U+2A7F</td></tr><tr><td>⪁</td><td>LESS-THAN OR SLANTED EQUAL TO WITH DOT ABOVE</td><td>U+2A81</td></tr><tr><td>⪃</td><td>LESS-THAN OR SLANTED EQUAL TO WITH DOT ABOVE RIGHT</td><td>U+2A83</td></tr><tr><td>⪅</td><td>LESS-THAN OR APPROXIMATE</td><td>U+2A85</td></tr><tr><td>⪇</td><td>LESS-THAN AND SINGLE-LINE NOT EQUAL TO</td><td>U+2A87</td></tr><tr><td>⪉</td><td>LESS-THAN AND NOT APPROXIMATE</td><td>U+2A89</td></tr><tr><td>⪍</td><td>LESS-THAN ABOVE SIMILAR OR EQUAL</td><td>U+2A8D</td></tr><tr><td>⪕</td><td>SLANTED EQUAL OR LESS-THAN</td><td>U+2A95</td></tr><tr><td>⪗</td><td>SLANTED EQUAL OR LESS-THAN WITH DOT INSIDE</td><td>U+2A97</td></tr><tr><td>⪙</td><td>DOUBLE-LINE EQUAL TO OR LESS-THAN</td><td>U+2A99</td></tr><tr><td>⪛</td><td>DOUBLE-LINE SLANTED EQUAL TO OR LESS-THAN</td><td>U+2A9B</td></tr><tr><td>⪝</td><td>SIMILAR TO OR LESS-THAN</td><td>U+2A9D</td></tr><tr><td>⪟</td><td>SIMILAR ABOVE LESS-THAN ABOVE EQUALS SIGN</td><td>U+2A9F</td></tr><tr><td>⪡</td><td>DOUBLE NESTED LESS-THAN</td><td>U+2AA1</td></tr><tr><td>⪣</td><td>DOUBLE NESTED LESS-THAN WITH UNDERBAR</td><td>U+2AA3</td></tr><tr><td>⪦</td><td>LESS-THAN CLOSED BY CURVE</td><td>U+2AA6</td></tr><tr><td>⪨</td><td>LESS-THAN CLOSED BY CURVE ABOVE SLANTED EQUAL</td><td>U+2AA8</td></tr><tr><td>⫷</td><td>TRIPLE NESTED LESS-THAN</td><td>U+2AF7</td></tr><tr><td>⫹</td><td>DOUBLE-LINE SLANTED LESS-THAN OR EQUAL TO</td><td>U+2AF9</td></tr><tr><td>﹤</td><td>SMALL LESS-THAN SIGN</td><td>U+FE64</td></tr><tr><td>＜</td><td>FULLWIDTH LESS-THAN</td><td>U+FF1C</td></tr></tbody></table>

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

Less-than sign

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 ${\displaystyle \prec }$ 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 ≺ PRECEDES.