Compilare: main.cpp: In function 'int main()': main.cpp:13:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 13 | for (int i = 1, j = 0; i < needle.size(); i++) | ~~^~~~~~~~~~~~~~~ main.cpp:25:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 25 | while (i < haystack.size()) | ~~^~~~~~~~~~~~~~~~~ main.cpp:30:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | if (j == needle.size()) | ~~^~~~~~~~~~~~~~~~