编写程序，验证一个字符串是否为回文串：是否从前读它和从后读它都是一样的。例如，mom，dad是回文串。该程序接收用户输入的字符串，判断是否为回文串，然后将判断的结果输出。在验证回文串时，忽略大小写、空格和标点。示例输出如图所示。(Write a program to verify whether a string is a palindrome string: whether it was read before and after reading it is the same. For exa