Compilare: main.cpp: In function 'bool calcul(std::__cxx11::string)': main.cpp:28:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind==s.size()) ~~~^~~~~~~~~~ main.cpp:54:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind==s.size()) ~~~^~~~~~~~~~ main.cpp:66:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind==s.size()) ~~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:94:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.size();++i) ~^~~~~~~~~ main.cpp:97:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<b.size();++i) ~^~~~~~~~~ main.cpp: In function 'bool calcul(std::__cxx11::string)': main.cpp:76:1: warning: control reaches end of non-void function [-Wreturn-type] } ^