In C #, you can only enter a number and set the upper limit in a TextBox control

First, you can enter only numbers:

First, set the KeyPress event for the TextBox control: When the user presses the key of the keyboard is not in the digital bit, it is forbidden to enter

1    Private void textbox1_keypress (object  sender, KeyPressEventArgs e)2         {  3             if8 &&! Char.isdigit (E.keychar))// If you do not enter a number, do not let input 4             {5                 true ; 6              }7         }

Set the upper limit:

Set the TextChanged event for the textbox as follows

1  Private voidtextBox1_TextChanged (Objectsender, EventArgs e)2         {3             intIMax = -;//first set the upper value4             if(TextBox1.Text! =NULL&& TextBox1.Text! ="")//determines that the contents of the textbox are not NULL, and if not judged will result in subsequent non-numeric contrast anomalies5             {6                 if(int. Parse (TextBox1.Text) > IMax)//num is the value passed in, if it is greater than the upper limit (the input value), then it is forced to 1, or the upper limit value? 7                 {8TextBox1.Text = (IMax-1). ToString ();9                 }Ten             } One}

In C #, you can only enter a number and set the upper limit in a TextBox control