Compilare: main.cpp: In function 'int main()': main.cpp:130:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (fr[v[i]] <= pos[v[i]].size()){ ~~~~~~~~~^~~~~~~~~~~~~~~~~~~ main.cpp: In member function 'char InParser::read_ch()': main.cpp:18:29: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^