foreach loop and array values

Question

I am writing a simple foreach loop to read key values from appconfig file. For some reason the array string called server looses previous values each time the foreach loop increments. Once the program runs to completion I see values as (server[0] = null, server[1]=null, server[2] = ). Only the last array pointer server[3] retains the values.

My questions are:

Why does the server[0] and server[1] become null.

How can I retain all the array values and pass them outside the foreach loop?

private void button2_Click(object sender, EventArgs e)
{
    int i = 0;
    int max = 0;
    string[] server;

    foreach (string key in System.Configuration.ConfigurationManager.AppSettings)
    {
        max = max + 1;
    }

    foreach (string key in System.Configuration.ConfigurationManager.AppSettings)
    {
        server = new string[max];
        server[i] = key;
        MessageBox.Show(server[i]).ToString();
        i = i + 1;
    }
}

Evan Mulawski · Accepted Answer · 2011-08-23 19:59:13Z

11

server = new string[max];

Should be outside the loop (in your case, between the two), otherwise you create a new array every iteration. This explains why the last value is correct, and the rest are empty.

Also, you can use ++ instead of i + 1 and max + 1.

answered Aug 23, 2011 at 19:59

Evan Mulawski

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1 Comment

Shazam Over a year ago

Thanks! I completely overlooked the issue.

cdhowie · Accepted Answer · 2011-08-23 20:06:33Z

3

What Evan said -- also, consider using LINQ to make your code more readable, and avoid similar bugs:

var server = System.Configuration.ConfigurationManager.AppSettings
             .Cast<string>().ToList();

foreach (string key in server)
    MessageBox.Show(key);

edited Aug 23, 2011 at 20:06

answered Aug 23, 2011 at 20:00

cdhowie

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Comments

Cloudy · Accepted Answer · 2011-08-23 20:05:52Z

0

Evan is exactly right. In addition to that, I recommend replacing the first foreach loop with

max = System.Configuration.ConfigurationManager.AppSettings.Count;

answered Aug 23, 2011 at 20:05

Cloudy

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