Julia provides an extremely flexible system for naming variables. Variable names are case-sensitive, and have no semantic meaning (that is, the language will not treat variables differently based on their names).
julia> ix = 1.0
1.0
julia> y = -3
-3
julia> Z = "My string"
"My string"
julia> customary_phrase = "Hello world!"
"Hello world!"
julia> UniversalDeclarationOfHumanRightsStart = "人人生而自由，在尊严和权力上一律平等。"
"人人生而自由，在尊严和权力上一律平等。"Unicode names (in UTF-8 encoding) are allowed:
julia> δ = 0.00001
1.0e-5
julia> 안녕하세요 = "Hello"
"Hello"Julia will even let you redefine built-in constants and functions if needed:
julia> pi
π = 3.1415926535897...
julia> pi = 3
Warning: imported binding for pi overwritten in module Main
3
julia> pi
3
julia> sqrt = 4
4However, this is obviously not recommended to avoid potential confusion.
Variable names must begin with a letter (A-Z or a-z), underscore, or Unicode character with code point greater than 00A0. Subsequent characters may also include ! and digits (0-9).
All operators are also valid identifiers, but are parsed specially. In some
contexts operators can be used just like variables; for example (+) refers
to the addition function, and (+) = f will reassign it.
The only explicitly disallowed names for variables are the names of built-in statements:
julia> else = false
ERROR: syntax: unexpected "else"
julia> try = "No"
ERROR: syntax: unexpected "="While Julia imposes few restrictions on valid names, it has become useful to adopt the following conventions:
- Names of variables are in lower case.
- Word separation can be indicated by underscores (
'\_'), but use of underscores is discouraged unless the name would be hard to read otherwise. - Names of
Types begin with a capital letter and word separation is shown with CamelCase instead of underscores. - Names of
functions andmacros are in lower case, without underscores. - Functions that modify their inputs have names that end in
!. These functions are sometimes called mutating functions or in-place functions.