Compilare: main.cpp: In function 'int NOT()': main.cpp:70:21: warning: array subscript has type 'char' [-Wchar-subscripts] return val[s[i - 1]]; ^ main.cpp: At global scope: main.cpp:75:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] main() ^ main.cpp: In function 'int main()': main.cpp:80:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < t.size(); i++) ~~^~~~~~~~~~ main.cpp:83:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(t[i] == 'O' && i + 1 < t.size() && t[i + 1] == 'R') ~~~~~~^~~~~~~~~~ main.cpp:89:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(t[i] == 'N' && i + 2 < t.size() && t[i + 1] == 'O' && t[i + 2] == 'T') ~~~~~~^~~~~~~~~~ main.cpp:95:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(t[i] == 'A' && i + 2 < t.size() && t[i + 1] == 'N' && t[i + 2] == 'D') ~~~~~~^~~~~~~~~~ main.cpp:112:8: warning: array subscript has type 'char' [-Wchar-subscripts] val[c] ^= 1; ^