两个简单的扩展方法：TrimPrefix和TrimSuffix

今天写程序频繁用到两中字符串操作：删除某个字符串指定的前缀和后缀。由于没有现成的方法可用，写了两个扩展方法：TrimPrefix和TrimSuffix。

namespace System

   2: {

class StringExtensions

   4:     {

false)

   6:         {

string.Empty;

if(!sourceString.StartsWith(prefix,ignoreCase, CultureInfo.CurrentCulture))

   9:             {

return sourceString;

  11:             }

  12:  

return sourceString.Remove(0, prefix.Length);

  14:         }

  15:  

false)

  17:         {

string.Empty;

if (!sourceString.EndsWith(suffix, ignoreCase, CultureInfo.CurrentCulture))

  20:             {

return sourceString;

  22:             }

return sourceString.Substring(0, sourceString.Length - suffix.Length);

  24:         }

  25:     }

  26: }