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
{
    public static class StringExtensions
    {
        public static string TrimPrefix(this string sourceString, string prefix, bool ignoreCase = false)
        {
            prefix = prefix ?? string.Empty;
            if(!sourceString.StartsWith(prefix,ignoreCase, CultureInfo.CurrentCulture))
            {
                return sourceString;
            }

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

        public static string TrimSuffix(this string sourceString, string suffix, bool ignoreCase = false)
        {
            suffix = suffix ?? string.Empty;
            if (!sourceString.EndsWith(suffix, ignoreCase, CultureInfo.CurrentCulture))
            {
                return sourceString;
            }
            return sourceString.Substring(0, sourceString.Length - suffix.Length);
        }
    }
}

程序调用：

static void Main(string[] args)
{
    string sourceString = "ABC123";
    Console.WriteLine(sourceString.TrimPrefix("ABC"));
    Console.WriteLine(sourceString.TrimSuffix("123"));
}

输出结果：

123
ABC