Compilare: main.cpp: In function 'bool f1()': main.cpp:23:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i + 3 < s.size() && s[i] == ' ' && s[i + 1] == 'O' && s[i + 2] == 'R' && s[i + 3] == ' ') { ~~~~~~^~~~~~~~~~ main.cpp: In function 'bool f2()': main.cpp:33:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i + 4 < s.size() && s[i] == ' ' && s[i + 1] == 'A' && s[i + 2] == 'N' && s[i + 3] == 'D' && s[i + 4] == ' ') { ~~~~~~^~~~~~~~~~ main.cpp: In function 'bool f3()': main.cpp:43:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i + 3 < s.size() && s[i] == 'N' && s[i + 1] == 'O' && s[i + 2] == 'T' && s[i + 3] == ' ') { ~~~~~~^~~~~~~~~~ main.cpp: In function 'bool f4()': main.cpp:61:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i + 3 < s.size() && s[i] == 'T' && s[i + 1] == 'R' && s[i + 2] == 'U' && s[i + 3] == 'E') { ~~~~~~^~~~~~~~~~ main.cpp:65:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (i + 4 < s.size() && s[i] == 'F' && s[i + 1] == 'A' && s[i + 2] == 'L' && s[i + 3] == 'S' && s[i + 4] == 'E') { ~~~~~~^~~~~~~~~~ main.cpp:70:17: warning: array subscript has type 'char' [-Wchar-subscripts] ans = val[s[i]]; ^ main.cpp: In function 'int main()': main.cpp:84:8: warning: array subscript has type 'char' [-Wchar-subscripts] val[c] = !val[c]; ^ main.cpp:84:18: warning: array subscript has type 'char' [-Wchar-subscripts] val[c] = !val[c]; ^