/// <summary>
/// 数字按Step的步进递增
/// 0==>9 9==>A A==>Z Z==>0
/// a==>Z
/// z==>0
/// 其他字符跳过
/// </summary>
/// <param name="source">源字符串</param>
/// <param name="step">步进</param>
/// <returns>转化后的字符串</returns>
public static string IncLetterAndDigit(this String source, int step)
{
return(StringHelper.IncLetterAndDigit(source, step));
}