Compilare: user.cpp: In function ‘int s_to_i(std::string)’: user.cpp:9:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i <= x.size() - 1; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:25:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i <= recipe.size() - 1; ++i) { ^ user.cpp:33:99: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (recipe[x] != ' ' and recipe[x] != '(' and recipe[x] != ')' and x < recipe.size()) { ^