Compilare: user.cpp: In function ‘bool f(int)’: user.cpp:62:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(len > v[i].size()) return false; ^ user.cpp:70:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = len; j < v[i].size(); j++){ ^ user.cpp:78:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(len > v[i].size()) return false; ^ user.cpp:90:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = len; j < v[i].size(); j++){ ^ user.cpp: In function ‘char nextch()’: user.cpp:12:36: 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, fi); ^