foo.cc: In function ‘int main()’:
foo.cc:9:12: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    9 |     while(i<str1.size())
      |           ~^~~~~~~~~~~~
foo.cc:11:9: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   11 |         if(str1[i]!=ch)
      |         ^~
foo.cc:13:17: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
   13 |                 i++;
      |                 ^