Julia variable

Variable

A variable in Julia is a name associated with (or bound) to a value. I t does this when you want to store a value (for example, you get some values after doing some math, and you need to use them later). For example:

# 给变量 x 赋值为 10
julia> x = 10
10

# 用 x 的值做一些数学运算
julia> x + 1
11

# 重新给 x 赋值
julia> x = 1 + 1
2

# 您可以为变量赋给种类型的值，例如文本字符串等
julia> x = "Hello World!"
"Hello World!"

Julia provides an extremely flexible variable naming system. Variable names are case sensitive.

julia> x = 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。"

You can also use the Unicode character (UTF-8 encoding) to name it:

julia> δ = 0.00001
1.0e-5

julia> 안녕하세요 = "Hello"
"Hello"

In Julia REPL and several other Julia editing environments, you can type many Unicode math symbols by entering the backslash symbol name and then the label. For example, δ be typed by typing by \_2 s \delta or even by entering the value of the file by entering s \alpha tab - s \hat - tab α̂₂ α̂₂.

Julia even allows you to redefine the built-in constants and functions:

julia> pi
π = 3.1415926535897...

julia> pi = 3
Warning: imported binding for pi overwritten in module Main
3

julia> pi
3

julia> sqrt(100)
10.0

julia> sqrt = 4
    Warning: imported binding for sqrt overwritten in module Main
4

It is clear that such an approach is not encouraged.

The variable name available

Variable names must start with letters (a-z or A-Z), underscores, or a Unicode encoded pointer that points to a larger subset of pointers than 00A0; C haracters after the first place also include! and numbers (0-9 and other characters Nd/No), as well as other Unicode encoded pointers: donics and other modified markers (letters Mn/Mc/Me/Sk), some punctuation connectors (letter PCs), prime numbers, and others.

Operators like + identifiers, but require special resolution. I n some cases, operators can (+) be used like variables; (+) = f Most Unicode embellished ⊕ such as ⊕, are resolved to mid-embellished operators, and ⊗ = kron s kron to define ⊕ as a suffix Kronecker product).

Built-in keywords cannot be used as variable names:

julia> else = false
ERROR: syntax: unexpected "else"

julia> try = "No"
ERROR: syntax: unexpected "="

The naming specification

Although Julia has few restrictions on naming itself, try to follow certain naming conventions:

• Variable names use lowercase letters
• Words are separated by '_' but are not encouraged
• Type initials are capital letters, and hump - type separations are used between words.
• Function names and macro names use lowercase letters, not underscores to separate words.
• Modify the end of the function of the argument ! . Such functions are called mutating functions or in-place functions