Compilare: user.cpp: In function ‘bool del(node*&, int)’: user.cpp:41:36: warning: NULL used in arithmetic [-Wpointer-arith] ok = ok & (p->c.test(j) == NULL); ^ user.cpp: In function ‘int main()’: user.cpp:67:29: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[305]’ [-Wformat=] fscanf(f, "%s\n", &s); ^ user.cpp:78:29: warning: format ‘%s’ expects argument of type ‘char*’, but argument 3 has type ‘char (*)[305]’ [-Wformat=] fscanf(f, "%s\n", &s); ^ user.cpp:64:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d\n", &x); int n = x; ^ user.cpp:67:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%s\n", &s); ^ user.cpp:76:26: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d\n", &n); ^ user.cpp:78:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%s\n", &s); ^