Compilare: user.cpp: In function ‘int main()’: user.cpp:196:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<polo_op.size(); i++) ^ user.cpp:143:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.in", "r", stdin); ^ user.cpp:144:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("evaluare.out", "w", stdout); ^ user.cpp:148:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(a); ^ user.cpp: In function ‘int conv(char)’: user.cpp:131:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int calc(int, int, int)’: user.cpp:139:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ /tmp/ccWbaiE1.o: In function `main': user.cpp:(.text.startup+0x7e): warning: the `gets' function is dangerous and should not be used.