foo.cc: In member function 'void Array::input()':
foo.cc:12:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   12 |             scanf("%s",a);
      |             ~~~~~^~~~~~~~
foo.cc:13:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   13 |             scanf("%s",b);
      |             ~~~~~^~~~~~~~
In file included from /usr/include/string.h:495,
                 from /usr/include/c++/9/cstring:42,
                 from foo.cc:2:
In function 'char* strcat(char*, const char*)',
    inlined from 'void Array::lianjie()' at foo.cc:17:19,
    inlined from 'void Array::diaoyong()' at foo.cc:23:24,
    inlined from 'int main()' at foo.cc:34:15:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:128:33: warning: 'char* __builtin___strcat_chk(char*, const char*, long unsigned int)' accessing 100001 or more bytes at offsets 100004 and 4 may overlap 1 byte at offset 100004 [-Wrestrict]
  128 |   return __builtin___strcat_chk (__dest, __src, __bos (__dest));
      |          ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'char* strcat(char*, const char*)',
    inlined from 'void Array::lianjie()' at foo.cc:18:19,
    inlined from 'void Array::diaoyong()' at foo.cc:23:24,
    inlined from 'int main()' at foo.cc:34:15:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:128:33: warning: 'char* __builtin___strcat_chk(char*, const char*, long unsigned int)' accessing 100001 or more bytes at offsets 4 and 100004 may overlap 1 byte at offset 100004 [-Wrestrict]
  128 |   return __builtin___strcat_chk (__dest, __src, __bos (__dest));
      |          ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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