C#全角转换成半角并检查

新建一个项目quanbanjiao，在此项目下新建一个类Class1

 using System;
 using System.Web;
 using System.Text;
 
 namespace quanbanjiao
 {
     public class Class1
     {
         /**/
         /// <summary>
         /// 判断字符是否英文半角字符或标点
         /// </summary>
         /// <remarks>
         /// 32    空格
         /// 33-47    标点
         /// 48-57    0~9
         /// 58-64    标点
         /// 65-90    A~Z
         /// 91-96    标点
         /// 97-122    a~z
         /// 123-126  标点
         /// </remarks>
         public static bool IsBjChar(char c)
         {
             int i = (int)c;
             return i >=  && i <= ;
         }
 
         /**/
         /// <summary>
         /// 判断字符是否全角字符或标点
         /// </summary>
         /// <remarks>
         /// <para>全角字符 - 65248 = 半角字符</para>
         /// <para>全角空格例外</para>
         /// </remarks>
         public static bool IsQjChar(char c)
         {
             if (c == '\u3000') return true;
 
             int i = (int)c - ;
             if (i < ) return false;
             return IsBjChar((char)i);
         }
 
         /* http://www.cnblogs.com/roucheng/ */
         /// <summary>
         /// 将字符串中的全角字符转换为半角
         /// </summary>
         public static string ToBj(string type,string s)
         {
             if (s == null || s.Trim() == string.Empty) return s;
 
             StringBuilder sb = new StringBuilder(s.Length);
             for (int i = ; i < s.Length; i++)
             {
                 if (s[i] == '\u3000')
                     sb.Append('\u0020');
                 else if (IsQjChar(s[i]))
                     sb.Append((char)((int)s[i] - ));
                 else
                     sb.Append(s[i]);
             }
 
             //如果是int类型的，则只能输入int类型，否则自动设为0
 
             if (type.ToLower() == "int")
             {
                 try
                 {
                     Convert.ToInt32(sb.ToString());
                 }
                 catch
                 {
                     return "";
                 }
 
             }
 
             //如果是float或double类型的，则只能输入这两种类型，否则自动设为0
             if (type.ToLower() == "float" || type.ToLower() == "double")
             {
                 try
                 {
                     Convert.ToDouble(sb.ToString());
                 }
                 catch
                 {
                     return "";
                 }
             }
             return sb.ToString();
         }
     }
 }

测试的例子：

using System;
using System.Web;
using quanbanjiao;//项目名称为quanbanjiao
 
namespace quanbanjiao
{
    public partial class WebForm1 : System.Web.UI.Page
    {
// keleyi.com
        protected void Page_Load(object sender, EventArgs e)
        {
        }
 
        protected void Button1_Click(object sender, EventArgs e)
        {
            TextBox1.Text = Class1.ToBj("string", TextBox1.Text.Trim());
        }
    }
}