C#判断中英文混合字符串长度及截取函数

using System.Text.RegularExpressions; using System.Text; /// <summary> /// 字符串长度(按字节算) /// </summary> /// <param name="str"></param> /// <returns></returns> static int StrLength(string str) {     int len = 0;     byte[] b;     for (int i = 0; i < str.Length; i++)     {         b = Encoding.Default.GetBytes(str.Substring(i,1));         if (b.Length > 1)             len += 2;         else             len++;     }     return len; } /// <summary> /// 截取指定长度字符串(按字节算) /// </summary> /// <param name="str"></param> /// <param name="length"></param> /// <returns></returns> static string StrCut(string str, int length) {     int len = 0;     byte[] b;     StringBuilder sb = new StringBuilder();     for (int i = 0; i < str.Length; i++)     {         b = Encoding.Default.GetBytes(str.Substring(i, 1));         if (b.Length > 1)             len += 2;         else             len++;         if (len >= length)             break;         sb.Append(str[i]);     }     return sb.ToString(); }