Compilare: user.cpp: In function ‘void dfs(tree*, int, int, char)’: user.cpp:59:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if ((nod->ok == 0 && nod->val.size() == na) || ad == 0) { ^ user.cpp:71:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(nod->ok == 1 && nod -> val.size() == na) ^ user.cpp: In function ‘int main()’: user.cpp:81:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &na); ^ user.cpp:84:27: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(a[i], LG + 2, fin); ^ user.cpp:91:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d", &nb); ^ user.cpp:94:27: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(b[i], LG + 2, fin); ^