Compilare: user.cpp: In function ‘int main()’: user.cpp:30:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i_str < str.size()){ ^ user.cpp:32:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < pat.size() && pat[i_pat + j] == str[i_str + j]){ ^ user.cpp:34:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j == pat.size()){ ^