.NET自动截取字符串前面是字母的函数

因为自己项目开发的需要，需要自己写个函数用于获取料件编号前缀，因为料件编号前缀是用料件类型然后加随机数字组成的，但是料件类型可能是1个，2个，3个等字母开头，我也不可能每个类型都判断，这样是否很难编码这个字符处理代码。其实仔细构思想了下 ，就有了如下代码了，自己做下CODE记录吧。

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.VisualBasic;
using System.Text.RegularExpressions;
namespace ConsoleAppTest
{
public    class StringHandle
    {
        /// <summary>
        /// 返回前缀为字母的字符串
        /// </summary>
        /// <param name="sourceString">要检测的字符串</param>
        /// <returns></returns>
        public static string getPreCharecterString(string sourceString)
        {
            char[] initialChar ={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
                'A','B','C','D','E','F','G','H','I','G','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};//52个字母
            //string initialString = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
            //char[] initialDigit ={ '0','1','2','3','4','5','6','7','8','9'};
            // initialChar=initialString.ToCharArray();
            if (string.IsNullOrEmpty(sourceString))
            {
                return string.Empty;
            }
            else
            {
                string tempStr = string.Empty;// 用于暂存
                char[] sourceChar = sourceString.ToCharArray();//把原来的字符转正字符数组
                int length = sourceString.Length;//获取字符串长度
                for (int i = 0; i < length; )
                { 
                //if (Regex.IsMatch(sourceChar[i].ToString(), @"^[+-]?\d*[.]?\d*$"))//匹配是否是数字，是则直接转向OK标签
                //{
                //    goto ok;
                //}
                    if (!Regex.IsMatch(sourceChar[i].ToString(), @"^[A-Za-z]"))//匹配非字母
                    {
                        goto ok;
                    }
                    char currentChar = sourceChar[i];
                    foreach(char okChar in initialChar)
                    {
                        if (okChar == currentChar)
                        {
                            tempStr += okChar;
                        }
                    }
                    i++;
                }
            ok:
                return tempStr;
            }
        }
}