foo.cc: In member function 'void expr::scan()':
foo.cc:62:19: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   62 | for (i=0,j=0,k=0;i<strlen(ts);i++)
      |                  ~^~~~~~~~~~~
foo.cc:78:7: warning: 'char* strcat(char*, const char*)' accessing 101 or more bytes at offsets 100 and 0 may overlap 1 byte at offset 100 [-Wrestrict]
   78 | strcat(ts,s);
      | ~~~~~~^~~~~~

[Hydro](https://hydro.ac)提供评测服务