Only allowing up to three digit numeric characters in a text box

Question

Is there a way to only allow a user to input a maximum number of characters into a text box? I want the user to input a mark/grade and only be able to input 0 - 100. Below I

Answer 1

This version set textBox1.Text to empty string if fail to parse

private void textBox1_TextChanged(object sender, EventArgs e) {
    int i;

    textBox1.Text=
        false==int.TryParse(textBox1.Text, out i)||0>i||i>100
            ?""
            :i.ToString();
}

If you want to keep the partial successfully parsed number then

String previousText="";

private void textBox1_TextChanged(object sender, EventArgs e) {
    var currentText=textBox1.Text;
    int i;

    textBox1.Text=
        int.TryParse(currentText, out i)
            ?0>i||i>99
                ?previousText
                :i.ToString()
            :""==currentText?currentText:previousText;

    previousText=textBox1.Text;
}