Compilare: main.cpp: In function 'str expresie()': main.cpp:14:15: warning: array subscript has type 'char' [-Wchar-subscripts] while (s[i] == 'S') { ^ main.cpp: In function 'str termen()': main.cpp:30:15: warning: array subscript has type 'char' [-Wchar-subscripts] while (s[i] == 'P') { ^ main.cpp: In function 'str factor()': main.cpp:46:12: warning: array subscript has type 'char' [-Wchar-subscripts] if (s[i] == '(') { ^ main.cpp:52:16: warning: array subscript has type 'char' [-Wchar-subscripts] if (s[i] == 'B') { ^ main.cpp: In function 'int main()': main.cpp:65:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses] in >> s+1; ~^~