Compilare: user.cpp: In function ‘void ToPolish()’: user.cpp:28:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] pol[ind++]=' '; ^ user.cpp:31:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] pol[ind]=op.top(); ^ user.cpp:39:22: warning: array subscript has type ‘char’ [-Wchar-subscripts] pol[ind++]=' '; ^ user.cpp:42:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] pol[ind]=op.top(); ^ user.cpp:56:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] pol[ind]=' '; ^ user.cpp:63:26: warning: array subscript has type ‘char’ [-Wchar-subscripts] pol[ind++]=c; ^ user.cpp:67:54: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(!op.empty()) { pol[ind+1]=op.top(); pol[ind]=' '; ind+=2; op.pop(); } ^ user.cpp: In function ‘void Number(char*)’: user.cpp:86:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<strlen(c);++i) ^ /tmp/ccdDKR5x.o: In function `main': user.cpp:(.text.startup+0x11): warning: the `gets' function is dangerous and should not be used.