Compilare: user.cpp: In function ‘int main()’: user.cpp:3:75: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;char v[5001];int main(){freopen("bunicu.in","r",stdin);freopen("bunicu.out","w",stdout);int t,n,i,j,k;char c;cin>>t;for(i=1; i<=t; i++){cin>>n>>ws;for(k=1; k<=n; k++){c=getchar();j=1;while(c!='\n'){if(j==k)cout<<(c=='0');c=getchar();++j;}}cout<<'\n';}return 0;} ^ user.cpp:3:108: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;char v[5001];int main(){freopen("bunicu.in","r",stdin);freopen("bunicu.out","w",stdout);int t,n,i,j,k;char c;cin>>t;for(i=1; i<=t; i++){cin>>n>>ws;for(k=1; k<=n; k++){c=getchar();j=1;while(c!='\n'){if(j==k)cout<<(c=='0');c=getchar();++j;}}cout<<'\n';}return 0;} ^