A Textbox Validation (Only Doubles) Needs C# Gurus :-)

Question

I want accept such number formats in my textbox. These numbers are all doubles.

2.6
45e-2
23e32
+0.05
-0.07e+5

So my textBox must allow these:

Maximum one "e" or "E" letter
"e" or "E" letter can't be at the end or at the beginning
"+" and "-" characters are allowed
"+" or "-" character can be only at the beginning of the number or behind the "e" OR "E" letter
All conditions must be valid for ctrl+V, mouse paste or typing
Maximum one "." charater before a number but not after an "e" letter.

What code do you suggest me? Thanks for all...

Dorababu Meka · Answer

Then you can simply write under button click event like Regex reg = new Regex("^[+-]?([0-9]*\.?[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$"); if (reg.IsMatch( textBox1.Text )) { } else { MessageBox.Show("Invalid value"); } Check my attachment

Dorababu Meka · Answer

That I got it when you enter some thing like 23e32 what you are trying to do?

Dorababu Meka · Answer

Try this REGEX ("^[+-]?([0-9]*\.?[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$");

Ali G · Answer

Thank you very much. Tonight I will try this...

Dorababu Meka · Answer

Better handling if ((e.KeyCode >= Keys.D0 && e.KeyCode (e.KeyCode >= Keys.NumPad0 && e.KeyCode { e.SuppressKeyPress = false; } else { e.SuppressKeyPress = true; }

Dorababu Meka · Answer

For blocking you can do this private void textBox1_KeyDown(object sender, KeyEventArgs e) { if (e.KeyCode == Keys.E) { e.SuppressKeyPress = false; } else { e.SuppressKeyPress = true; } } And for validating you can show a message box as per I said if it is a invalid one

Ali G · Answer

Yes others must be blocked. And E can't be at he end or beginnig of the number...

Dorababu Meka · Answer

So you would like to block all the other letters?

Ali G · Answer

Exactly... User can enter E letter but not other letters...

Ali G · Answer

I am trying to make a unit converter software. But input must be double precision. Now I am trying your ============================= Regex reg = new Regex("^[+-]?([0-9]*\.?[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$"); if (reg.IsMatch(textBox1.Text)) { } else { MessageBox.Show("Invalid value"); } ============================== code. It seems OK but I need develeop the contrent of those codes. Thanks for all..

Dorababu Meka · Answer

Ali G can you explain what you are trying to achieve

Dorababu Meka · Answer

Can you post some sample out put what you are exactly trying to do, what is your text box value and what you need? But as per your question you said you have to accept some of the given values and valid

Ali G · Answer

I am trying to make a converter but input must be only double number...

Dorababu Meka · Answer

I didn't get what you are trying to do with your code and if your requirement is to valid the sequences as per you said try the one which I posted, if any let me know

Ali G · Answer

Thank you very much. I am writing a windows form software and trying to find a place to paste your codes :-) MY CODES ARE HERE: using System; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { Double DoubleKatsayi1 = 1; Double DoubleKatsayi2 = 1; if (listBox1.SelectedIndex == -1) { listBox1.SelectedIndex = 0; } if (listBox2.SelectedIndex == -1) { listBox2.SelectedIndex = 0; } Double DoubleSayi = Double.Parse(textBox1.Text); switch (listBox1.SelectedItem.ToString()) { case "meter": DoubleKatsayi1 = 1; break; case "decimeter": DoubleKatsayi1 = 0.1; break; case "centimeter": DoubleKatsayi1 = 0.01; break; case "milimeter": DoubleKatsayi1 = 0.001; break; } switch (listBox2.SelectedItem.ToString()) { case "meter": DoubleKatsayi2 = 1; break; case "decimeter": DoubleKatsayi2 = 0.1; break; case "centimeter": DoubleKatsayi2 = 0.01; break; case "milimeter": DoubleKatsayi2 = 0.001; break; } Double DoubleSonuc = DoubleSayi * (DoubleKatsayi1 / DoubleKatsayi2); textBox2.Text = DoubleSayi.ToString() + " " + listBox1.SelectedItem.ToString() + " = " + DoubleSonuc.ToString() + " " + listBox2.SelectedItem.ToString(); } private void button2_Click(object sender, EventArgs e) { int index1 = listBox1.SelectedIndex; int index2 = listBox2.SelectedIndex; listBox1.SelectedIndex = index2; listBox2.SelectedIndex = index1; } } }

Dorababu Meka · Answer

If you would like to validate using text box with regular expression validation you can do like this ValidationExpression="^[+-]?([0-9]*\.?[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$" ErrorMessage="Not Valid" ForeColor="Red">

Dorababu Meka · Answer

Sample code StringBuilder sbvalid = new StringBuilder(); StringBuilder sbInvalid = new StringBuilder(); Regex reg = new Regex("^[+-]?([0-9]*\.?[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$"); List lst = new List (); lst.Add("2.6"); lst.Add("45e-2"); lst.Add("23e32"); lst.Add("+0.05"); lst.Add("0.07e+5"); lst.Add("23.17.5"); foreach (string strReg in lst) { if (reg.IsMatch(strReg)) { sbvalid.AppendLine(strReg); } else { sbInvalid.AppendLine(strReg); } } And if you would like to match with text box means Regex reg = new Regex("^[+-]?([0-9]*\.?[0-9]+|[0-9]+\.?[0-9]*)([eE][+-]?[0-9]+)?$"); if (reg.IsMatch(youtextbox.Text)) { ///Valid } else { ///Invalid }

Ali G · Answer

Can you help me about the syntax? I am newbee..

A Textbox Validation (Only Doubles) Needs C# Gurus :-)

Answers (18)