Variables

In V variables can be declared and initialized with the := operator. Variables can only be declared this way in V, this means all variables have an initial value. The type of a variable is inferred from the value on the right hand side. By default variables in V are immutable.
age := 23               // int
name := 'Alice'         // string
is_adult := age > 21    // bool
​
println(age_str)        // 23
println(name)           // Alice
println(is_adult)       // true
Note: Variables can only be defined in a function. There are no global variables and no global state in V.
To change the value of a variable, it needs to be mutable. This can be done using the mut keyword when declaring the variable. To assign a new value to a variable use =.
mut age := 20       // declare the mutable variable age and assign it to the value 20.
println(age)        // 20
age = 21            // assign a new value to age
println(age)        // 21
Leaving out the mut keyword here would result in an error because the value of an immutable variable cannot be changed.
fn main() {
    age = 20
    println(age)
}
The code above would result in an error during compilation because the variable age is not declared,
fn main() {
    mut age := 20       // we declare the mutable variable age and assign it to the value 20.
    println(age)        // 20
    age := 21           // ERROR
}
here age := 21 will result in another error while compiling because the variable age is already defined in the scope. It's very simple to remember, just declare value with := and assign value with =.
Like Go, You can also use _ for ignoring values when it is not needed. Usually used in multi return functions.
_ := "I don't need this value"
println(_) // ERROR: Cannot use `_` as value
Naming Rules
The following are the rules which should be kept in mind while naming variables.
Name should not contain Uppercase letters like AlphaTest
Use underscores as separators like hello_world
Name should be descriptive as possible
Name should not contain __
Name should not contain any space
If the name is longer than 11 then it must use _ as separator
These rules are from Snake_Case. V uses Snake Case and prefers it because it is more easy to read, write and understand.
Valid Names
boby
john_dads
myfamily_number
Invalid Names
IamNotValid
new Make
Keywords
Formatted Print
Last modified 3yr ago