foo.cc:9:16: warning: multi-character character constant [-Wmultichar]
  while(s[len]!='/0')
                ^~~~
foo.cc: In function 'int main()':
foo.cc:35:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s",s);           //s为要处理的加密字符串，答案储存在ans里
     ~~~~~^~~~~~~~

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