Compilare: user.cpp: In function ‘int main()’: user.cpp:52:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while((p<v[l].size())&&(v[l][p].a!=x)){ ^ user.cpp:55:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(p<v[l].size()){ ^ user.cpp:67:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0; j<v[i].size(); j++){ ^ user.cpp: In function ‘char nextch()’: user.cpp:16:37: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, BUF_SIZE, 1, fin); ^