Compilare: user.cpp: In function ‘int main()’: user.cpp:50:22: warning: ISO C++ forbids converting a string constant to ‘char*’ [-Wwrite-strings] input f("mine.in"); ^ user.cpp:83:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t j = 1; j <= nv; j++) { ~~^~~~~ user.cpp:51:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mine.out", "w", stdout); ^ user.cpp: In constructor ‘input::input(char*)’: user.cpp:27:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(s, "r", stdin); ^ user.cpp:29:37: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, 1, dim, stdin); ^ user.cpp: In member function ‘void input::operator>>(int&)’: user.cpp:35:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, 1, dim, stdin); ^ user.cpp:42:45: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer, 1, dim, stdin); ^