Compilare: user.cpp: In function ‘bool Prel_str(std::string*, char*)’: user.cpp:29:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < sizeof(v); i++) ^ user.cpp:36:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i + 1 >= c.size()){ ^ user.cpp: In function ‘int main()’: user.cpp:74:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < sizeof(vec); j++) ^