Compilare: main.cpp: In function 'int search(std::string)': main.cpp:18:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 18 | if (cate_now == mid && p < b.size()) | ~~^~~~~~~~~~ main.cpp:20:9: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 20 | if (p==b.size()) | ~^~~~~~~~~~ main.cpp: At global scope: main.cpp:30:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] 30 | main () | ^~~~