Compilare: user.cpp: In function ‘std::vector<int> intersectie(std::vector<int>&, std::vector<int>&)’: user.cpp:21:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()){ ^ user.cpp:21:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()){ ^ user.cpp: In function ‘std::vector<int> reuniune(std::vector<int>, std::vector<int>)’: user.cpp:45:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()){ ^ user.cpp:45:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()){ ^ user.cpp:46:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a[i] > b[j] && j < b.size()){ ^ user.cpp:56:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a[i] < b[j] && i < a.size()){ ^ user.cpp: In function ‘std::vector<int> diferenta(std::vector<int>, std::vector<int>)’: user.cpp:83:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()){ ^ user.cpp:83:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i < a.size() && j < b.size()){ ^ user.cpp:84:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a[i] > b[j] && j < b.size()){ ^ user.cpp:93:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a[i] < b[j] && i < a.size()){ ^ user.cpp: In function ‘int main()’: user.cpp:147:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expr.in", "r", stdin); ^ user.cpp:148:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expr.out", "w", stdout); ^ user.cpp:151:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a); ^ /tmp/ccPiuvDc.o: In function `main': user.cpp:(.text.startup+0x82): warning: the `gets' function is dangerous and should not be used.