 #include <stdlib.h> #include <stdio.h>  typedef struct node_tag {     int value;     struct node_tag *next; } node_t;  int main(void) {     char const *filename = "test.txt";     FILE *input_file = fopen(filename, "r");     if (!input_file) {         fprintf(stderr, "Couldn't open \"%s\" for reading :(\n\n", filename);         return EXIT_FAILURE;     }      // read from file and build a list:     