Compilare: user.cpp: In function ‘vvi royfloyd(vvi&)’: user.cpp:15:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto k = 0u; k < n; ++k) ^ user.cpp:16:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto i = 0u; i < n; ++i) { ^ user.cpp:19:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto j = 0u; j < n; ++j) { ^ user.cpp: In function ‘int main()’: user.cpp:33:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto i = 0u; i < n; ++i) ^ user.cpp:34:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto j = 0u; j < n; ++j) { ^ user.cpp:40:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto i = 0u; i < n; ++i, fprintf(fout, "\n")) ^ user.cpp:41:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (auto j = 0u; j < n; ++j) ^ user.cpp:31:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &n); ^ user.cpp:36:36: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &val); ^