How to use message box inside a loop

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When i try to show messagebox on a condition , message box also looping on each data adding on listbox . I also gave messagebox outside the loop . still it's the same .
i want to show messagebox only once if condition is true

What I have tried:

C#

var dataReader = sqlDataReader1;
while (dataReader.Read())
{
    string q = listBox1.Items.Count.ToString();
    string a = Settings.Default["outercode"].ToString();

    label4.Text = "(" + q + "/" + a + ")";
    listBox1.Items.Add(dataReader[0]);
    if (Convert.ToInt32(q) < Convert.ToInt32(a))
    {
        //MessageBox.Show("No sufficient Unit codes");
    }
}

Posted 30-May-21 6:56am

Member 15212425

Updated 30-May-21 7:06am

Dave Kreskowiak

v2

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BillWoodruff 31-May-21 2:54am

Until you clarify what you want to achieve, how can we help you ? What works, what doesn't work; what errors, what error messages and, where do errors or unexpected results. What do you expect the runb-time user to do ?

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Wendelius · Accepted Answer · 2021-05-30T07:05:00

You can for example use a boolean variable to indicate that the message is already shown. Something like

C#

var dataReader = sqlDataReader1;
bool messageShown = false;
while (dataReader.Read())
{
   string q = listBox1.Items.Count.ToString();
   string a = Settings.Default["outercode"].ToString();

   label4.Text = "(" + q + "/" + a + ")";
   listBox1.Items.Add(dataReader[0]);
   if (!messageShown && Convert.ToInt32(q) < Convert.ToInt32(a))
   {
      MessageBox.Show("No sufficient Unit codes");
      messageShown = true;
   }
}

EDIT

Looking at the solution you've posted, it looks like you would like to fill the listbox and if the amount of items is less than your setting then you'd like to show a message box. If that is correct, then the code could look something like

C#

var dataReader = sqlDataReader1;
int requiredAmount = (int)Settings.Default["outercode"];
while (dataReader.Read())
{
   label4.Text = $"({listBox1.Items.Count}/{requiredAmount})";
   listBox1.Items.Add(dataReader[0]);
} 
if (listBox1.Items.Count < requiredAmount) 
{
   MessageBox.Show("No sufficient Unit codes");
}

Note that the code above will cause an exception if the setting is missing or cannot be converted to int so you may want to use Int32.TryParse Method (System) | Microsoft Docs[^] and in general add proper error handling using try-catch - C# Reference | Microsoft Docs[^]

To better understand how your code works, refer to Tutorial: Debug C# code - Visual Studio | Microsoft Docs[^] to better understanding for debugging the code.