Constants in Julia

Our code example demonstrates the use of constants in the target language. Here’s the complete source code translated to Julia.

# Declare a constant value
const s = "constant"

function main()
    println(s)
    
    # Constant declaration
    const n = 500000000
    
    # Constant expression with arbitrary precision arithmetic
    const d = 3e20 / n
    println(d)
    
    # Explicit conversion of the constant expression to Int64
    println(Int64(d))
    
    # Using a numeric constant in a context that requires a specific type
    println(sin(n))
end

main()

To execute the code, ensure you have Julia installed and run the code using the Julia interpreter.

$ julia constant.jl

The expected output will be:

constant
6.0e+11
600000000000
-0.28470407323754404

In this program:

• We declare constants using the const keyword.
• Constants can be arithmetic expressions with arbitrary precision.
• A numeric constant has no type until given one by explicit conversion or by usage in a context that requires a type.
• The sin function is used with a numeric constant, demonstrating type inference in a required context.

Now that we have an understanding of constants in Julia, let’s explore more features of the language.