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| < | |
|---|---|
Less-than sign | |
| In Unicode | U+003C <LESS-THAN SIGN (<, <) |
| Related | |
| See also | similar symbolslisted below |
Theless-than sign is a mathematical symbol that denotes aninequality 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 include1 < 4 and−2 < 0.
Since the development of computerprogramming languages, the less-than sign and the greater-than sign have been repurposed for a range of uses and operations.
Theless-than sign,<, is an originalASCII character (hex 3C, decimal 60).
InBASIC,Lisp-family languages, andC-family languages (includingJava andC++),comparison operator< means "less than".
InColdfusion, operator.lt. means "less than".
InFortran, operator.LT. means "less than"; later versions allow<.
InBourne shell (and many other shells), operator-lt means "less than". Less-than sign is used toredirect input from a file. Less-than plus ampersand (<&) is used to redirect from afile descriptor.
Thedouble less-than sign,<<, may be used for an approximation of themuch-less-than sign (≪) or of the openingguillemet («). ASCII does not encode either of these signs, though they are both included inUnicode.
InBash,Perl, andRuby, operator<<EOF (where "EOF" is an arbitrary string, but commonly "EOF" denoting "end of file") is used to denote the beginning of ahere document.
InC andC++, operator<< represents abinary left shift.
In theC++ Standard Library, operator<<, when applied on an output stream, acts asinsertion operator and performs an output operation on the stream.
InRuby, operator<< acts asappend operator when used between an array and the value to be appended.
InXPath the<< operator returns true if the left operand precedes the right operand in document order; otherwise it returns false.[1]
InPHP, operator<<<OUTPUT is used to denote the beginning of aheredoc statement (whereOUTPUT is an arbitrary named variable.)
In Bash,<<<word is used as a "here string", whereword is expanded and supplied to the command on its standard input, similar to a heredoc.
The less-than sign with the equals sign,<=, may be used for an approximation of theless-than-or-equal-to sign,≤. ASCII does not have a less-than-or-equal-to sign, butUnicode defines it at code point U+2264.
InBASIC,Lisp-family languages, andC-family languages (includingJava andC++), operator<= means "less than or equal to". InSinclair BASIC it is encoded as a single-byte code point token.
InProlog,=< means "less than or equal to" (as distinct from the arrow<=).
InFortran, operators.LE. and<= both mean "less than or equal to".
InBourne shell andWindows PowerShell, the operator-le means "less than or equal to".
In theR programming language, the less-than sign is used in conjunction with ahyphen-minus to create an arrow (<-), this can be used as the left assignment operator.
The less-than sign is used in thespaceship operator.
InHTML (andSGML andXML), 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,≤, may be included with≤.
Unicode provides variousless 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 |
| ≮ | NOT LESS THAN | U+226E |
| ≰ | NEITHER LESS-THAN NOR EQUAL TO | U+2270 |
| ≲ | LESS-THAN OR EQUIVALENT TO | U+2272 |
| ≴ | NEITHER LESS-THAN NOR EQUIVALENT TO | U+2274 |
| ⋖ | LESS-THAN WITH DOT | U+22D6 |
| ⋘ | VERY MUCH LESS-THAN | U+22D8 |
| ⋜ | EQUAL TO OR LESS-THAN | U+22DC |
| ⋦ | LESS-THAN BUT NOT EQUIVALENT TO | U+22E6 |
| ⍃ | 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 |
| ⩻ | LESS-THAN WITH QUESTION MARK ABOVE | U+2A7B |
| ⩽ | LESS-THAN OR SLANTED EQUAL TO | U+2A7D |
| ⩿ | 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 |
| ⫷ | TRIPLE NESTED LESS-THAN | U+2AF7 |
| ⫹ | DOUBLE-LINE SLANTED LESS-THAN OR EQUAL TO | U+2AF9 |
| ﹤ | SMALL LESS-THAN SIGN | U+FE64 |
| ＜ | FULLWIDTH LESS-THAN | U+FF1C |
The less-than sign may be seen for an approximation of the openingangle bracket,⟨. True angle bracket characters, as required inlinguistics notation, are expected in formal texts.
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 atotal order,partial order orpreorder. However, the symbol is often used when it would be confusing or not convenient to use<. In mathematical writing usingLaTeX, theTeX command is\prec. The Unicodecode point isU+227A ≺PRECEDES.