Compilare: main.cpp: In function 'int main()': main.cpp:107:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] { for(j=0; j<a[0][i].size(); j++) ~^~~~~~~~~~~~~~~ main.cpp:115:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<a[1][i].size(); j++) ~^~~~~~~~~~~~~~~ main.cpp:123:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<a[2][i].size(); j++) ~^~~~~~~~~~~~~~~ main.cpp: In member function 'char InParser::read_ch()': main.cpp:21:29: 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); ^