/// <summary>
/// 指定文本倒序
/// </summary>
/// <param name="str">文本</param>
/// <returns>倒序文本</returns>
public static string StrReverse(string str)
{
    char[] chars = str.ToCharArray();
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < chars.Length; i++)
    {
        sb.Append(chars[chars.Length - 1 - i]);
    }
    return sb.ToString();
}