Compilare: user.cpp: In function ‘int main()’: user.cpp:38:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<final.size();++i) ^ user.cpp:41:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i!=final.size()-1) printf(","); ^ user.cpp: In function ‘std::vector<int> intersectie(std::vector<int>, std::vector<int>)’: user.cpp:69:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<B.size();++i) ^ user.cpp: In function ‘std::vector<int> reuniune(std::vector<int>, std::vector<int>)’: user.cpp:85:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<A.size();++i) ^ user.cpp:88:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<B.size();++i) ^ user.cpp: In function ‘std::vector<int> diferenta(std::vector<int>, std::vector<int>)’: user.cpp:102:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<A.size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:26:29: 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:27:31: 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:29:10: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(S+1); ^ /tmp/ccpq59lt.o: In function `main': user.cpp:(.text.startup+0x5c): warning: the `gets' function is dangerous and should not be used.