# 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.

## Contents

## Computing[edit]

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[edit]

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[edit]

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.

In Ruby, operator `<<` acts as *append operator* when used between an array and the value to be appended.

### Triple less-than sign[edit]

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[edit]

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".

### Less-than sign plus Hyphen-minus[edit]

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[edit]

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[edit]

Less-than sign is used in the spaceship operator.

### HTML[edit]

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 may be included with `≤`

.

## Mathematics[edit]

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.