Error handling (try-catch)

This lesson covers error handling with Julia's try-catch, with the aim of keeping a program running even when something unexpected goes wrong.

try / catch / end catches an error so the whole program does not stop. Think of it as insurance: deciding in advance what to do instead, should something fail.

In the sample code, a divide() function raises an error with error() on division by zero, and try ... catch e ... end catches it. Note that catch e gives you the error information in the variable e.

A common early stumble is how flexible the syntax is. It works without naming a variable after catch, but you need one to get at the details of the error.

In professional work, try-catch is used around anything that can fail, such as reading data or a numerical routine that may not converge.

📖 Reference code

function divide(a, b)
    if b == 0
        error("cannot divide by zero")
    end
    a / b
end

try
    println(divide(10, 2))
    println(divide(10, 0))
catch e
    println("Error: ", e.msg)
end

✍️ Your code

Type your code, then press "Run"

🧪 This site can't compile or run Julia directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser — nothing is sent anywhere).