Compilare: main.cpp: In function 'void show(const std::vector<int>&)': main.cpp:13:28: warning: format '%i' expects argument of type 'int', but argument 2 has type 'std::vector<int>::size_type {aka long unsigned int}' [-Wformat=] printf("%i\n", A.size()); ^ main.cpp: In function 'std::vector<int> operator*(std::vector<int>, std::vector<int>)': main.cpp:23:10: warning: variable 'it' set but not used [-Wunused-but-set-variable] auto it = set_intersection(A.begin(), A.end(), B.begin(), B.end(), inserter(R, R.begin())); ^~ main.cpp: In function 'std::vector<int> operator+(std::vector<int>, std::vector<int>)': main.cpp:30:10: warning: variable 'it' set but not used [-Wunused-but-set-variable] auto it = set_union(A.begin(), A.end(), B.begin(), B.end(), inserter(R, R.begin())); ^~ main.cpp: In function 'int main()': main.cpp:92:19: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'char (*)[1001]' [-Wformat=] scanf("%s", &s); ^ main.cpp:66:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("multimi4.in", "r", stdin); ^ main.cpp:67:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("multimi4.out", "w", stdout); ^ main.cpp:68:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%i", &N); ^ main.cpp:73:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s); ^ main.cpp:92:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", &s); ^