handling Throw exception in Julia

In Julia, an exception can be thrown using the throw() function. An exception is typically thrown when there is an error or an unexpected condition within a function.

Here's an example which throws an ArgumentError if the input argument to the function is less than 0:

function myfunc(x)
    if x < 0
        throw(ArgumentError("Input argument must be non-negative."))
    end
    return sqrt(x)
end

Now, let's test this function with different input values:

julia> myfunc(4)
2.0
julia> myfunc(-4)

ERROR: ArgumentError: Input argument must be non-negative.

Stacktrace:

 [1] myfunc(::Int64) at ./REPL[1]:3

 [2] top-level scope at REPL[2]:1

As we can see from the output, the function works perfectly fine with non-negative input values and throws an ArgumentError when the input value is negative.

Similarly, we can also define our own custom exceptions and throw them whenever required:

struct MyException <: Exception
    message::String
end
function myfunc2(x)

    if x == 0

        throw(MyException("Invalid input argument."))

    end

    return 1/x

end

Now, let's test this function with different input values:

julia> myfunc2(4)
0.25
julia> myfunc2(0)

ERROR: MyException("Invalid input argument.")

Stacktrace:

 [1] myfunc2(::Int64) at ./REPL[5]:3

 [2] top-level scope at REPL[6]:1

As we can see, the function throws our custom MyException when the input argument is 0.