学步园

/// <summary><br /> /// 求字符串的实际长度（汉字2个字节，外语字符1个字节）<br /> /// </summary><br /> /// <param name="str"></param><br /> /// <returns></returns><br /> public static int Length(string str)<br /> {<br /> int len = 0;<br /> char[] arr = str.ToCharArray();<br /> for (int i = 0; i < arr.Length; i++)<br /> {<br /> //汉字<br /> if (Asc(arr[i].ToString()) == -1)<br /> len += 2;<br /> else<br /> len += 1;<br /> }</p> <p> return len;<br /> }</p> <p>/// <summary><br /> /// 重写截取字符串方法，这里的长度是字节数（汉字2个字节，外语字符1个字节）<br /> /// </summary><br /> /// <param name="str"></param><br /> /// <param name="length">截取长度（这里的长度是字节数，汉字2个字节，外语字符1个字节）</param><br /> /// <returns></returns><br /> public string Substring(string str, int length)<br /> {<br /> int len = 0;<br /> char[] arr = str.ToCharArray();<br /> string strReturn = string.Empty;</p> <p> //参数检查<br /> if (length > Length(str))<br /> length = Length(str);</p> <p> for (int i = 0; i < arr.Length; i++)<br /> {<br /> //汉字<br /> if (Asc(arr[i].ToString()) == -1)<br /> len += 2;<br /> else<br /> len += 1;</p> <p> if (len > length)<br /> break;</p> <p> strReturn += arr[i].ToString();<br /> }</p> <p> return strReturn;<br /> }</p> <p>/// <summary><br /> /// 字符转ASCII码，如果未能转换为ASCII码返回-1<br /> /// </summary><br /> /// <param name="character"></param><br /> /// <returns></returns><br /> public static int Asc(string character)<br /> {<br /> if (character.Length == 1)<br /> {<br /> //因为汉字和?都被转换为63，所以?进行提前处理<br /> if (character == "?")<br /> return 63;</p> <p> System.Text.ASCIIEncoding asciiEncoding = new System.Text.ASCIIEncoding();<br /> int intAsciiCode = (int)asciiEncoding.GetBytes(character)[0];</p> <p> //如果未能转换为ASCII码（暂且认为为汉字）<br /> if (intAsciiCode == 63)<br /> return -1;</p> <p> return (intAsciiCode);<br /> }<br /> else<br /> {<br /> throw new Exception("Character is not valid.");<br /> }<br /> }</p> <p>/// <summary><br /> /// ASCII码转字符<br /> /// </summary><br /> /// <param name="asciiCode"></param><br /> /// <returns></returns><br /> public static string Chr(int asciiCode)<br /> {<br /> if (asciiCode >= 0 && asciiCode <= 255)<br /> {<br /> System.Text.ASCIIEncoding asciiEncoding = new System.Text.ASCIIEncoding();<br /> byte[] byteArray = new byte[] { (byte)asciiCode };<br /> string strCharacter = asciiEncoding.GetString(byteArray);<br /> return (strCharacter);<br /> }<br /> else<br /> {<br /> throw new Exception("ASCII Code is not valid.");<br /> }<br /> }<br />

 关于ASCII码的转换参考：

http://blog.csdn.net/ldw701/archive/2006/06/01/767875.aspx