We Keep Coding

Finding which textbox is empty

I have short windows program I use to add information quickly. But now I'm trying to enhance it.
Was looking for a more efficient want to check for empty text boxes and if the box was empty to find which one it was and set the focus back to only that box. Currently I loop through all of them and check to see if any box was empty if it is just display a message. But have to look to see which box is missing text. Heres the code:
bool txtCompleted = true;
string errorMessage = "One or more items were missing from the form";
foreach(Control c in Controls)
{
if (c is TextBox)
{
if (String.IsNullOrEmpty(c.Text))
{
txtCompleted = false;
}
}
}
if (txtCompleted == false)
{
MessageBox.Show(errorMessage);
}

Your approach using foreach looks promising to me. Howver you can use LINQ as well
if(this.Controls.OfType<TextBox>().Any(t => string.IsNullOrEmpty(t.Text)) {
...
}
You can use the focus() method to set the focus to the empty text box.

Set the focus on the control while in your loop, then break when done.
foreach(Control c in Controls)
{
if (c is TextBox)
{
if (String.IsNullOrEmpty(c.Text))
{
txtCompleted = false;
c.Focus();
MessageBox.Show(errorMessage);
break;
}
}
}

To get a reference to the empty textbox you use almost the same solution as R.T. presents, but use FirstOrDefault instead:
var emptyTextBox = Controls.OfType<TextBox>().FirstOrDefault(t => string.IsNullOrEmpty(t.Text)
if (emptyTextBox != null)
{
// there is a textbox that has no Text set
// set focus, present error message etc. on emptyTextBox
}

Looping throughTextBoxes in a Panel

I have a panel that contains 5 textboxes, I am trying to loop through the Panel and insert the value of the textbox into the database if it is not 0.
my panel name is Panel1
I honestly do not know from where to start or how to loop in a Panel that contains textfields, any suggestions are appreciated:
Here is my try which it does not compile (I am not sure how to write a loop that loops through a panel)
const string query = "INSERT INTO deductible (number) VALUES (#yes)";
using (var command = new SqlCommand(query, conn))
{
foreach (Panel1 c in this.Controls)
{
if (c.ToString() != "0")
{
command.Parameters.AddWithValue("#yes", c.Text);
command.ExecuteNonQuery();
}
}
I also attached a screenshot of my Panel1.
Thank you.

The simple answer is
foreach(Control control in this.Controls) {
if (control is TextBox) {
// The code here ...
}
}
The problem though is that you then need to make sure that the order the textboxes are looped over is correct, which adds more maintenance work that is entirely unnecessary. A better approach would be to learn about data binding. Or even more simply, just name your textboxes and assign them directly. Either of those is preferable to using a loop I think.

One way is to iterate each control within your Panel that is a TextBox.
foreach (TextBox tb in Panel1.Controls.OfType<TextBox>())
{
if (tb.Text != "0")
{
}
}

You're trying to loop through items of type Panel1 in this.Controls. What you want to do is loop through items of type TextBox in Panel1.Controls.
foreach(Control c in Panel1.Controls) {
var textbox = Control As TextBox;
if(textbox != null){
// do stuff...
}
}
You also want to look at the Text property of the TextBox, not call ToString on it.
if(textbox.Text != "0"){ //do stuff... }
And you add a #yes parameter to the same command multiple times within the loop, without clearing out the parameters list. I'm not certain if that will work, but if it causes a problem, you should just be able to call command.Parameters.Clear to clear the old parameter before adding the new one.

Text from textboxes to list

I'm REALLY new to C# and programming overall, so my question might be stupid in your opinion but here it is.
I have created a form which contains 7 textboxes and i want to collect text from these textboxes and add them to a list. I however get an error saying, System.Windows.Forms.TextBox is a 'type' but is used like a 'variable". What should I do?
for (int i = 1; i < 8; i++)
{
if (TextBox[i].Text == "")
{
days.Add("Restday");
}
else
{
days.Add(TextBox[i].Text);
}
}

TextBox is a type. so TextBox[i] is causing you trouble.
You can alway do something like this
foreach(Control ctrl in yourform.Controls)
{
Textbox = ctrl as TextBox;
if(txtBox != null)
{
if (txtBox.Text == "")
{
days.Add("Restday");
}
else
{
days.Add(txtBox.Text);
}
}
}
This work for a basic form. If you have pannel and other container to organize your controls the approch described in Guffa answer might be better. This could also be rewritten as method who accept a collection of Control recursive use to reach all controls.

Put the textbox references in an array so that you can easily loop through them. If your textboxes are named TextBox1 to TextBox7:
TextBox[] boxes = {
TextBox1, TextBox2, TextBox3, TextBox4, TextBox5, TextBox6, TextBox7
};
foreach (TextBox box in boxes) {
if (box.Text == "") {
days.Add("Restday");
} else {
days.Add(box.Text);
}
}

I guess you don't have an array named TextBox that is why the error. You can try following:
List<strig> days = this.Controls.OfType<TextBox>
.Select(r=> string.IsNullOrWhiteSpace(r.Text)
? "Restday" : r.Text)
.ToList();
But the above would give you the textboxes added on the form directly, If these textboxes are inside other control then you can look for recursively

Go into the form editor and select one of your textboxes. Now find the properties window. If it's not visible then click View->Properties Window
One of the properties in there will be the name of the textbox control. Use that to access it's text value like so:
days.Add(txtMyTextboxName.Text);
If you must iterate through the textboxes you can do this:
foreach(var Textbox in this.Controls.OfType<TextBox>())
{
if (Textbox.Text == "")
{
days.Add("Restday");
}
else
{
days.Add(Textbox.Text);
}
}
But bear in mind this is a pretty non-standard approach and not recommended.

How can I check multiple textboxes if null or empty without a unique test for each?

I have about 20 text fields on a form that a user can fill out. I want to prompt the user to consider saving if they have anything typed into any of the text boxes. Right now the test for that is really long and messy:
if(string.IsNullOrEmpty(txtbxAfterPic.Text) || string.IsNullOrEmpty(txtbxBeforePic.Text) ||
string.IsNullOrEmpty(splitContainer1.Panel2) ||...//many more tests
Is there a way I could use something like an Array of any, where the array is made of the text boxes and I check it that way? What other ways might be a very convenient way in which to see if any changes have been made since the program started?
One other thing I should mention is there is a date time picker. I don't know if I need to test around that as the datetimepicker will never be null or empty.
EDIT:
I incorporated the answers into my program, but I can't seem to make it work correctly.
I set up the tests as below and keep triggering the Application.Exit() call.
//it starts out saying everything is empty
bool allfieldsempty = true;
foreach(Control c in this.Controls)
{
//checks if its a textbox, and if it is, is it null or empty
if(this.Controls.OfType<TextBox>().Any(t => string.IsNullOrEmpty(t.Text)))
{
//this means soemthing was in a box
allfieldsempty = false;
break;
}
}
if (allfieldsempty == false)
{
MessageBox.Show("Consider saving.");
}
else //this means nothings new in the form so we can close it
{
Application.Exit();
}
Why is it not finding any text in my text boxes based on the code above?

Sure -- enumerate through your controls looking for text boxes:
foreach (Control c in this.Controls)
{
if (c is TextBox)
{
TextBox textBox = c as TextBox;
if (textBox.Text == string.Empty)
{
// Text box is empty.
// You COULD store information about this textbox is it's tag.
}
}
}

Building on George's answer, but making use of some handy LINQ methods:
if(this.Controls.OfType<TextBox>().Any(t => string.IsNullOrEmpty(t.Text)))
{
//Your textbox is empty
}

public void YourFunction(object sender, EventArgs e) {
string[] txtBoxArr = { textBoxOne.Text, textBoxTwo.Text, textBoxThree.Text };
string[] lblBoxArr = { "textBoxOneLabel", "textBoxTwoLabel", "textBoxThreeLabel" };
TextBox[] arr = { textBoxOne, textBoxTwo, textBoxThree };
for (int i = 0; i < txtBoxArr.Length; i++)
{
if (string.IsNullOrWhiteSpace(txtBoxArr[i]))
{
MessageBox.Show(lblBoxArr[i] + " cannot be empty.");
arr[i].Focus();
return;
}
}
}

DynamicRadio Button

I'm using C# in VS2005. For my application I need to create four radio buttons. My form looks like:
A(Radio Button)
B(Radio Button)
C(Radio Button)
D(Radio Button)
Submit (Button)
When a user clicks the submit button I need to know which radio button is checked. How can I determine this?

I would add all the radio buttons to a List<RadioButton> which would help you innumerate through them when the submit is checked to figure out which one is checked.

You can use the Checked Property of a RadioButton to see if it is checked:
bool isChecked = radA.Checked;
I often use the following helper function to get exactly the RadioButton which is checked:
public RadioButton GetCheckedRadioButton(Control container)
{
if (container == null) {
return null;
}
else if (container is RadioButton) {
return GetCheckedRadioButton(container.Parent);
}
else {
foreach (Control childControl in container.Controls) {
if (childControl is RadioButton) {
RadioButton radioBtn = (RadioButton) childControl;
if (radioBtn.Checked) {
return radioBtn;
}
}
}
return null;
}
}
Then, you can simply call this function using one of your controls or it's container, and do a switch statement, as such:
switch(GetCheckedRadioButton(radA)) {
case radA:
// radA is checked
break;
case radB:
// radB is checked
break;
}
Personally, I find it less verbose than the usual:
if(radA.Checked) {
//radA is checked
}
else if(radB.Checked) {
//radB is checked
}

If you know for sure that you will only need 4 RadioButtons, then I'd just write code similar to this.
if (Radio1.Checked) ...
if (Radio2.Checked) ...
if (Radio3.Checked) ...
...
If you know that only one of them can be checked at the same time (using a group box or some other mechanism) then you can optimise this by using "else if" instead.
However if there is a possibility that you will need more, this can get wasteful, so I agree with other answers, you should put them in a collection of your choice and use it to loop through them, to see which ones are checked.