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 typical mathematical usage, the less-than sign is typically placed between the two values being compared and signals 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 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.

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 Fortran, operator .LE. means "less than or equal to".

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

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.

See also

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.