Need help with creating list of methods and randomly call methods from list

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This code create List of methods and random function is working but if i call lista(); it will throw function over and over again - it will not remove them from list, so i will get: TrecePitanje() next PrvoPitanje() next PrvoPitanje() next PrvoPitanje() next TrecePitanje() next DrugoPitanje() .... and so on.
Ps sorry for mine english.

C#

public void lista()
        {
       

            var actionList = new[]
                {
                    new Action( () => PrvoPitanje() ),
                    new Action( () => DrugoPitanje() ),
                    new Action( () => TrecePitanje() )
                }.ToList();
            
        
            label4.Text = actionList.Count().ToString(); // To Check -1 
            
            while (actionList.Count() > 0)
            {
            var r = new Random();
            var index = r.Next(actionList.Count());
            var action = actionList[index];
            actionList.RemoveAt(index);
            action();
            }




        }

What I have tried:

If i try to count methods in list with

C#

label4.Text = actionList.Count().ToString();

everything looks ok. What i doing wrong?

Posted 13-Oct-16 5:17am

Member 11383935

Updated 13-Oct-16 5:35am

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#realJSOP · Answer 1 · 2016-10-13T05:35:00

When you do this

C#

new Action(()=>methodname())

You're executing the methods. Is that really what you want?

Try something like this instead.

C#

// Use a list instead of casting a var to a list (that's inefficient)
List<Action> actionList = List<Action>()
{
    // there's no need to do "new Action here"
    PrvoPitanje,
    DrugoPitanje,
    TrecePitanje
};

// instantiate the random object outside the loop
Random r = new Random();
// while we have an action in the list
while (actionList.Count() > 0)
{
    // If the list contains more than one item, randomly select the index.
    // Otherwise, just take the first and only item in the list (there's
    // no use in randomly selecting the next item when there's only one in
    // the list.
    int index = (actionList.Count > 1) ? r.Next(0,actionList.Count()-1) : 0;
    // execute the action
    actionList[index]();
    // remove it from the list
    actionList.RemoveAt(index);
}

I would also stop using var unless absolutely necessary. Just because the language has a given feature doesn't mean it should be used (I dislike the use of var - it's a personal thing).

OriginalGriff · Answer 2 · 2016-10-13T05:30:00

The problem may be that you are creating the Random instance inside your loop - and Random initialises itself from the system clock, so if two instances are created close together, they are more than likely going to get the same time, and thus generate the same sequence.

Always create your Random instance as a private class level instance:

C#

private Random rand = new Random();
        public void lista()
        {
            var actionList = new[]
                {
                    new Action( () => PrvoPitanje() ),
                    new Action( () => DrugoPitanje() ),
                    new Action( () => TrecePitanje() )
                }.ToList();
            label4.Text = actionList.Count().ToString(); // To Check -1 
            while (actionList.Count() > 0)
            {
                var index = rand.Next(actionList.Count());
                var action = actionList[index];
                actionList.RemoveAt(index);
                action();
            }

Then check that your methods don't call lista themselves!

Need help with creating list of methods and randomly call methods from list

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