Compilare: user.cpp: In function ‘void show(std::vector<int>)’: user.cpp:10:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<p.size();++i) ^ user.cpp: In function ‘void perm(std::vector<int>, int)’: user.cpp:16:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(p.size()==n){show(p);return;} ^ user.cpp: In function ‘int main()’: user.cpp:28:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permutari.in","r",stdin); ^ user.cpp:29:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permutari.out","w",stdout); ^ user.cpp:30:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^