Compilare: user.cpp: In function ‘void a_precalc(int)’: user.cpp:15:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < a.size()) ^ user.cpp: In function ‘void str_match(int)’: user.cpp:33:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < b.size()) ^ user.cpp:42:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i == a.size()) ^ user.cpp: In function ‘int main()’: user.cpp:72:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < b.size(); i++) ^ user.cpp:79:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < b.size(); j++) ^