This page uses content from Wikipedia and is licensed under CC BY-SA.

# Less-than sign

<
Less-than sign
In UnicodeU+003C < LESS-THAN SIGN (HTML `&#60;` · `&lt;`)
Related
See alsoU+2264 LESS-THAN OR EQUAL TO (HTML `&#8804;` · `&le;`)
U+226E NOT LESS-THAN (HTML `&#8814;`)
U+226A MUCH LESS-THAN (HTML `&#8810;`)
Different from
Different fromU+2329 LEFT-POINTING ANGLE BRACKET (HTML `&#9001;` · `&lang;`)

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 ½ < 1 and −2 < 1. 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 is used for an approximation of the opening angle bracket (⟨). ASCII does not have angle brackets.

### Programming language

In BASIC, Lisp-family languages, and C-family languages (including Java and C++), operator `<` means "less than".

In Coldfusion, operator `.lt.` means "less than".

In Fortran, operator `.LT.` means "less than"; later versions allow `<`.

In Bourne shell, operator `-lt` means "less than".

### Double less-than sign

The double less-than sign (`<<`) is used for an approximation of the much-less-than sign (≪) or of the opening guillemet («). ASCII does not have a much-less-than sign.

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 plus equals sign

The less-than sign plus the equals sign (`<=`) is 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, operator `.LE.` means "less than or equal to".

In Bourne shell and Windows PowerShell, the operator `-le` means "less than or equal to".

### Less-than sign plus 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.

### Shell scripts

In Bourne shell (and many other shells), less-than sign is used to redirect input from a file. Less-than plus ampersand (`<&`) is used to redirect from a file descriptor.

### Spaceship operator

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;`.

## Mathematics

In an inequality, the less-than sign always "points" to the smaller number. Put another way, the "jaws" (the wider section of the symbol) always direct to the larger number.

## References

1. ^ "XML Path Language (XPath) 2.0 (Second Edition)". www.w3.org. W3C. 14 December 2010. Retrieved 29 October 2019.