Compilare: user.cpp: In function ‘int main()’: user.cpp:104:27: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(FIN,"r",stdin); ^ user.cpp:105:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(FOUT,"w",stdout); ^ user.cpp:106:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&N); ^ user.cpp:107:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=0;i<N;i++) scanf("%s\n",var[i]); ^ user.cpp:108:35: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(expr,sizeof(expr),stdin); ^ user.cpp: In function ‘int factor()’: user.cpp:53:12: warning: ‘ret’ may be used uninitialized in this function [-Wmaybe-uninitialized] return ret; ^