How to restart a function when an if condition is met

Question

How do I "restart" my function when an if condition is or isn't met.
In this pseudocode, if the if condition is met, I would like to stop what the function was doing and restart again.

function example()

     .
     .
     .

 for i in 1:N
        for j in 1:N
            if Mat[i,j] > 1
                Mat[i,j] += restart? # Here the process should restart,
            end
        end
    end

This could mean a few different things. Can you elaborate? Do you mean you want to break out of the loop, restart the loop, break out of the whole function, or recursively call the function again? — cbk, Jul 24 '21 at 17:28

Mikael Öhman · Accepted Answer · 2021-07-26T12:43:08.343

2

Rather than adding additional branching and complicating a function, return values offer a great ability for control flow in I.M.H.O. much cleaner fashion. Adding a little separate function is simple

function do_thing_once!(mat)
    # Returns true if successful
    for i in 1:N
        for j in 1:N
            if mat[i,j] > 1
                mat[i,j] += 123
                return false
            end
        end
    end
    return true
end

function do_all_things!(mat)
    success = false
    while !success
        success = do_thing_once!(mat)
    end
end

edited Jul 26 '21 at 12:43

answered Jul 24 '21 at 19:29

Mikael Öhman

2,294
15
21

1

you don't need a second function if you use directly `return do_thing_once!(mat)` instead of `return false` – MarcMush Jul 24 '21 at 23:08
Sure, just be mindful of recursive functions as Julia lacks tail call optimization (yet) – Mikael Öhman Jul 25 '21 at 11:32
yes, but this approach is not practical if the function is supposed to return something – MarcMush Jul 25 '21 at 15:25
``` while not ``` is not a working command (or in other words, Julia treats "not" as a variable). Am I missing a Package? @MikaelÖhman – Struggling_Student Jul 26 '21 at 10:23
Wopps! I have been coding to much python recently. Should be fixed now I hope – Mikael Öhman Jul 26 '21 at 12:43

How to restart a function when an if condition is met

1 Answers1