Compilare: user.cpp: In function ‘std::vector<std::pair<char, int>, std::allocator<std::pair<char, int> > > evalp(std::string)’: user.cpp:26: warning: comparison between signed and unsigned integer expressions user.cpp:32: warning: comparison between signed and unsigned integer expressions user.cpp:45: warning: comparison between signed and unsigned integer expressions user.cpp:48: warning: name lookup of ‘i’ changed user.cpp:26: warning: matches this ‘i’ under ISO standard rules user.cpp:45: warning: matches this ‘i’ under old rules user.cpp: In function ‘int main()’: user.cpp:87: warning: comparison between signed and unsigned integer expressions user.cpp:82: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:83: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result