how to validate textbox that accepts only integers

Question

how to validate textbox that accepts only integers with backspace wants to work in c# windows application. i wrote keypress event its working for integers but backspace is not working.

Harsh Shah · Answer

private void textBox1_KeyPress(object sender, KeyPressEventArgs e) { if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) && (e.KeyChar != '.')) { e.Handled = true; } // only allow one decimal point if ((e.KeyChar == '.') && ((sender as TextBox).Text.IndexOf('.') > -1)) { e.Handled = true; } }

Amit Mohanty · Answer

Hey, please check below code. //1. allowed only numeric value ex.10 private void Number_KeyPress( object sender, KeyPressEventArgs e) { //allowed only numeric value ex.10 if (e.KeyChar >= 48 && e.KeyChar { e.Handled = false ; } else { e.Handled = true ; } } //2. allowed numeric and one dot ex. 10.23 private void Numeric_KeyPress( object sender, KeyPressEventArgs e) { // allowed numeric and one dot ex. 10.23 if (e.KeyChar >= 48 && e.KeyChar { e.Handled = false ; } else { e.Handled = true ; } // only allow one decimal point if (e.KeyChar == 46 && (sender as TextBox).Text.IndexOf( '.' ) > -1) { e.Handled = true ; } } //3. Allow only allow one decimal point, negative number and backspace private void NumberNegitive_KeyPress( object sender, KeyPressEventArgs e) { if (e.KeyChar >= 48 && e.KeyChar { e.Handled = false ; } else { e.Handled = true ; } // only allow one decimal point if (e.KeyChar == 46 && (sender as TextBox).Text.IndexOf( '.' ) > -1) { e.Handled = true ; } // allow negative Regex reg = new Regex(@ "^-?\d+[.]?\d*$" ); if (!reg.IsMatch((sender as TextBox).Text.Insert((sender as TextBox).SelectionStart, e.KeyChar.ToString()) + "1" )) { e.Handled = true ; } // allow backspace if (e.KeyChar == 8) { e.Handled = false ; } }

Amit Gupta · Answer

You can take advantage of numerucUpDown control that was made for this purpose only

Jaimin Shethiya · Answer

Hello Shipa, private void textBox1_KeyPress( object sender, KeyPressEventArgs e) { e.Handled = !Char.IsNumber(e.KeyChar) && e.KeyChar != 8; //8 is allow the backspace } Thanks

Sachin Singh · Answer

If you want to allow only numerics and backspace then the Key_Press event should be e.Handled = !Char.IsNumber(e.KeyChar) || e.KeyChar == '\b' ; Here is the code to check if backspace is pressed if (e.KeyChar == '\b' ){ //backspace was pressed }

Rajanikant Hawaldar · Answer

Below code accepts numbers and backspace. private void textBox1_KeyPress( object sender, KeyPressEventArgs e) { if (! char .IsControl(e.KeyChar) && ! char .IsDigit(e.KeyChar)) { e.Handled = true ; } }

how to validate textbox that accepts only integers

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Answers (6)