Compilare: user.cpp: In function ‘bool subsir(const string&, const string&)’: user.cpp:56:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(p = 0, i = 0; i < s2.length() && p < s1.length(); ++i) ^ user.cpp:56:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(p = 0, i = 0; i < s2.length() && p < s1.length(); ++i) ^ user.cpp:57:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(p < s1.length() && s1[p] != s2[i]) ++p; ^ user.cpp:59:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] return p < s1.length(); ^ user.cpp:54:15: warning: unused variable ‘a’ [-Wunused-variable] int i, p, a; ^