判断输入的字符是否是数字

private bool isNumber(string s)
{
int Flag = 0;
char[] str = s.ToCharArray();
for (int i = 0; i < str.Length; i++)
{
if (Char.IsNumber(str[i]))
{
Flag++;
}
else
{
Flag = -1;
break;
}
}
if (Flag > 0)
{
return true;
}
else
{
return false;
}
}

测试代码:

protected void TextBox1_TextChanged(object sender, EventArgs e)
{
if (isNumber(TextBox1.Text.Trim()))
{
DIV1.InnerHtml = ""<script>alert('输入的是数字');</script>";
return;
}
else
{
DIV1.InnerHtml = "<script>alert('请输入0-9的数字');</script>";
return;
}
}