Fields completion verify

Question

I have a form with some fields on it:

folderNameLabel
folderTitle
folderDescription
folderCategory

Before the user will press OK, I want to check if all that fields are not =="". I wanted to make a function to receive an array as parameter and return a bool value, but I am not sure how to write it...

score 0 · Answer 1 · answered Sep 14 '12 at 08:59

0

public bool Validate(List<string> parameters)
{
   foreach(string parameter in parameters)
   {
        if(String.IsNullOrEmpty(parameter))
        {
            return false;
        }
   }
   return true;
}

answered Sep 14 '12 at 08:59

Dmitrii Dovgopolyi

6,231
2
27
44

Thorsten Dittmar · Accepted Answer · 2012-09-14T09:20:48.080

0

You could do the following:

private void btnOK_Click(object sender, EventArgs e)
{
    bool fieldsFilled = ValidateStrings(folderNameLabel.Text, 
                                        folderTitle.Text, 
                                        folderDescription.Text, 
                                        folderCategory.Text);
    if (fieldsFilled)
        DialogResult = DialogResult.OK;
    else
    {
        // Report errors
    }
}

private bool ValidateStrings(params string[] items)
{
    bool result = true;
    for (int i = 0; i < items.Length && result; i++)
        result &= !String.IsNullOrWhitespace(items[i]);

    return result;
}

Question: How do you tell the user which field he missed?

In your case, you could show a "You need to fill in all fields" message, but having only one optional field, that doesn't work anymore. This is why usually you don't do something like above.

edited Sep 14 '12 at 09:20

answered Sep 14 '12 at 09:01

Thorsten Dittmar

55,956
8
91
139

This is what I wanted, I never known how to make a function to take an indefinite number of parameters. Thank you so much! – Sep 14 '12 at 09:04
1

That's short for `a = a && b;`. – Thorsten Dittmar Sep 14 '12 at 09:19
1

Actually, the loop can be optimized a bit - I'm modifying my answer accordingly. – Thorsten Dittmar Sep 14 '12 at 09:20
Bbut why is `for` better than `foreach`? – Sep 14 '12 at 09:25
It's not only that for arrays `for` is quicker (http://stackoverflow.com/questions/365615/in-net-which-loop-runs-faster-for-or-foreach), but the loop now exits at the first occurrence of an empty string and does not check the other strings because the result would still be `false`. – Thorsten Dittmar Sep 14 '12 at 09:31
Yeah, I found out already that the previous function did not work properly... You know what I mean: "does not check the other strings because the result would still be false" – Sep 14 '12 at 09:33
I forgot to click the button :)) – Sep 14 '12 at 09:34
Should have worked fine - only looping too much. `true && !String.IsNullOrWhitespace(...) == true` as long as the string is actually not blank. If it is blank, the result comes out as `false`. After that `false && whatever == false`. – Thorsten Dittmar Sep 14 '12 at 09:36
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/16682/discussion-between-victor-barbu-and-thorsten-dittmar) – Sep 14 '12 at 09:36
It doesn't still work properly... If I fill just one filed of the ones sent as parameters, the function returns `true` – Sep 14 '12 at 09:47
I just tried: `Console.WriteLine(ValidateStrings("Hello", ""));` which outputs `false` and `Console.WriteLine(ValidateStrings("Hello", "World"));`, which outputs `true`. Are you doing something else wrong? – Thorsten Dittmar Sep 14 '12 at 09:55
You were right, I corrected the some logical errors in my application – Sep 14 '12 at 10:15

Fields completion verify

2 Answers2