Compilare: main.cpp: In function 'int calc(int, int)': main.cpp:26:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 26 | for(int f = 1;f < A[i][j].size(); ++f){ | ~~^~~~~~~~~~~~~~~~ main.cpp:28:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 28 | while(f < A[i][j].size() && A[i][j][f] != '+') | ~~^~~~~~~~~~~~~~~~ main.cpp:33:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 33 | for(;g < str.size(); ++g) | ~~^~~~~~~~~~~~ main.cpp:38:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 38 | for(;g < str.size(); ++g) | ~~^~~~~~~~~~~~ main.cpp:16:6: warning: unused variable 'adun' [-Wunused-variable] 16 | bool adun = 0; | ^~~~ main.cpp:17:6: warning: unused variable 'form' [-Wunused-variable] 17 | bool form = 0; | ^~~~