Compilare: user.c: In function ‘read’: user.c:53: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result user.c:56: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result user.c: In function ‘main’: user.c:102: warning: passing argument 4 of ‘qsort’ from incompatible pointer type /usr/include/stdlib.h:756: note: expected ‘__compar_fn_t’ but argument is of type ‘long int (*)(const void *, const void *)’