C#中如何限制TextBox控件内输入值的范围
作者：Danny_hi
这篇文章主要介绍了C#中如何限制TextBox控件内输入值的范围，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教
C#限制TextBox控件内输入值的范围
比如要限制TextBox1控件内只能输入1~100的数字（先将TextBox1的MaxLength属性设置成3）：
1.首先要限制输入的只能是数值，不能是字母或其他符号；选择添加textBox1的KeyPress事件
代码如下：
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
if (!(Char.IsNumber(e.KeyChar)) && e.KeyChar != (char)8)
e.Handled = true;
2.再限制输入数值的范围1~100；选择添加textBox1的TextChanged事件
代码如下：
private void textBox1_TextChanged(object sender, EventArgs e)
if (textBox1.Text == "")
textBox1.Text = 0.ToString();
int number = int.Parse(textBox1.Text);
textBox1.Text = number.ToString();
if (number <= 100)
return;
textBox1.Text = textBox1.Text.Remove(2);
textBox1.SelectionStart = textBox1.Text.Length;
C#TextBox控件限制只允许输入数字及小数点
//判断按键是不是要输入的类型。
if (((int)e.KeyChar < 48 || (int)e.KeyChar > 57) && (int)e.KeyChar != 8 && (int)e.KeyChar != 46)
e.Handled = true;
//小数点的处理。
if ((int)e.KeyChar == 46) //小数点
if (textBox1.Text.Length <= 0)
e.Handled = true; //小数点不能在第一位
float f;
float oldf;
bool b1 = false, b2 = false;
b1 = float.TryParse(textBox1.Text, out oldf);
b2 = float.TryParse(textBox1.Text + e.KeyChar.ToString(), out f);
if (b2 == false)
if (b1 == true)
e.Handled = true;
e.Handled = false;
处理只输入数字的
private void tBox_KeyPress(object sender, KeyPressEventArgs e)
if (e.KeyChar == 0x20) e.KeyChar = (char)0; //禁止空格键
if ((e.KeyChar == 0x2D) && (((TextBox)sender).Text.Length == 0)) return; //处理负数
if (e.KeyChar > 0x20)
double.Parse(((TextBox)sender).Text + e.KeyChar.ToString());
catch
e.KeyChar = (char)0; //处理非法字符
private void TextBox_KeyPress(object sender, KeyPressEventArgs e)
if(e.KeyChar!=8&&!Char.IsDigit(e.KeyChar))
e.Handled = true;
private void TextBox_KeyPress(object sender, KeyPressEventArgs e)
if(e.KeyChar!='\b'&&!Char.IsDigit(e.KeyChar))
e.Handled = true;
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
if(e.KeyChar!='\b')//这是允许输入退格键
if((e.KeyChar<'0')||(e.KeyChar>'9'))//这是允许输入0-9数字
e.Handled = true;
private void textBox1_Validating(object sender, CancelEventArgs e)
const string pattern = @"^\d+\.?\d+{1}quot;;
string content = ((TextBox)sender).Text;
if (!(Regex.IsMatch(content, pattern)))
errorProvider1.SetError((Control)sender, "只能输入数字!");
e.Cancel = true;
errorProvider1.SetError((Control)sender, null);
private void textBox1_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
if(e.KeyChar=='.' && this.textBox1.Text.IndexOf(".")!=-1)
e.Handled=true;
if(!((e.KeyChar>=48 && e.KeyChar<=57) || e.KeyChar=='.' || e.KeyChar==8))
e.Handled=true;
private void tbx_LsRegCapital_KeyPress(object sender, KeyPressEventArgs e)
if (!Char.IsNumber(e.KeyChar) && !Char.IsPunctuation(e.KeyChar) && !Char.IsControl(e.KeyChar))
e.Handled = true;//消除不合适字符
else if (Char.IsPunctuation(e.KeyChar))
if (e.KeyChar != '.' || this.textBox1.Text.Length == 0)//小数点
e.Handled = true;
if (textBox1.Text.LastIndexOf('.') != -1)
e.Handled = true;
利用ASCII码处理办法、
if ((e.KeyChar <= 48 || e.KeyChar >=57) && (e.KeyChar != 8) && (e.KeyChar != 46))
e.Handled = true;
================48代表0，57代表9，8代表空格，46代表小数点
C# 文本框只能输入数字和退格键
private void TextBox_KeyPress(object sender, KeyPressEventArgs e)
if(e.KeyChar!=8&&!Char.IsDigit(e.KeyChar))
e.Handled = true;
