Your First Program

Create a file named hello.jl and run it with julia hello.jl:

println("Hello, world!")
println("Welcome to Julia.")

Expected output

Hello, world!
Welcome to Julia.

• println prints its arguments and then a new line.
• Strings go in double quotes. Single quotes are for a single character, like 'a'.
• No semicolons, no main function: Julia runs a file from top to bottom.

print, println, and several values

print("Loading")
print("...")
println(" done")
println("Answer: ", 42)
println(1, 2, 3)

Loading... done
Answer: 42
123

print doesn't add a new line. Both functions glue several arguments together without spaces, so add the spaces yourself.

@show

x = 6 * 7
@show x
@show x + 1

x = 42
x + 1 = 43

@show prints an expression and its value — the quickest way to peek at what your code is doing. (The @ marks a macro; you'll write your own in Level 3.)

Practice

Write a program that prints your name on one line and your favorite food on the next, then uses @show to print 2 + 2.

println("Ada")
println("Pizza")
@show 2 + 2

Ada
Pizza
2 + 2 = 4