Compilare: user.c: In function ‘main’: user.c:39:5: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration] arr = (int *) malloc(n * sizeof(int)); ^ user.c:39:19: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] arr = (int *) malloc(n * sizeof(int)); ^ user.c:49:5: warning: implicit declaration of function ‘free’ [-Wimplicit-function-declaration] free(arr); ^ user.c:49:5: warning: incompatible implicit declaration of built-in function ‘free’ [enabled by default] user.c:37:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &n); ^ user.c:42:15: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &arr[i]); ^