Compilare: user.c: In function ‘Build’: user.c:26:16: warning: comparison between pointer and integer [enabled by default] for (i = 0; i < n; ++i) { ^ user.c: In function ‘Add’: user.c:44:2: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration] dest = malloc(sizeof(node_t)); ^ user.c:44:9: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] dest = malloc(sizeof(node_t)); ^ user.c: In function ‘main’: user.c:53:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("metrou2.in", "r", stdin); ^ user.c:54:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("metrou2.out", "w", stdout); ^ user.c:55:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i%i", &n, &m); ^ user.c:57:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i", &p[i]); ^ user.c:60:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i%i", &a, &b); ^