Работа с файлами

#include <stdio.h>
#include <string.h>
#include <stddef.h>
#include <stdlib.h>
 
struct Student {
  char *name;
  char *surname;
  char *class_name;
};
 
struct StudentList {
  struct Student *students;
  size_t size;
  size_t capacity;
};
 
const k_recapacity = 1024;
void AddStudent(struct Student student, struct StudentList *student_list) {
  if (student_list->capacity == 0 && student_list->students == NULL) {
    student_list->students = (struct Student*)malloc(sizeof(struct Student) *
                             (student_list->capacity += k_recapacity));
  } else
  if (student_list->size == student_list->capacity) {
    struct Student *new_data = (struct Student*)malloc(sizeof(struct Student) *
                               (student_list->capacity + k_recapacity));
    int i;
    for (i = 0; i < student_list->size; ++i)
      new_data[i] = student_list->students[i];
    free(student_list->students);
    student_list->students = new_data;
    student_list->capacity += k_recapacity;
  }
  student_list->students[student_list->size++] = student;
}
void ClearStudents(struct StudentList *student_list) {
  int i;
  for (i = 0; i < student_list->size; ++i) {
    free(student_list->students[i].name);
    free(student_list->students[i].surname);
    free(student_list->students[i].class_name);
  }
  free(student_list->students);
  student_list->students = NULL;
  student_list->size = 0;
  student_list->capacity = 0;
}
 
int ReadString(char **destination, char *buffer, size_t buffer_size,
                FILE *infile) {
  int result = 0;
  if (result = (fgets(buffer, buffer_size, infile) != NULL)) {
    size_t buffer_length = strlen(buffer);
    if (buffer_length > 0) buffer[buffer_length - 1] = '\0';
    *destination = strcpy((char*)malloc(buffer_length + 1), buffer);
  } else {
    *destination = NULL;
  }
  return result;
}
 
int main(int argc, char *argv[]) {
  size_t buffer_size = 65536;
  FILE *infile = fopen("tutor36.c.txt", "r");
  struct StudentList student_list = { NULL, 0, 0 };
  if (infile == NULL) {
    printf("Could not open stream.\n");
  } else {
    char *buffer = (char*)malloc(buffer_size);
    while (!feof(infile)) {
      struct Student new_student = {NULL, NULL, NULL};
      if (ReadString(&new_student.name, buffer, buffer_size, infile) &&
          ReadString(&new_student.surname, buffer, buffer_size, infile) &&
          ReadString(&new_student.class_name, buffer, buffer_size, infile)) {
        AddStudent(new_student, &student_list);
      } else {
        fprintf(stderr, "Unexpected end of file.\n");
      }
    }
    free(buffer);
  }
 
  int i;
  for (i = 0; i < student_list.size - 1; ++i) {
    int j;
    for (j = i + 1; j < student_list.size; ++j)
      if (strcmp(student_list.students[i].surname,
          student_list.students[j].surname) == 0)
        printf("%s %s in %s has %s %s in %s.\n",
                               student_list.students[i].name,
                               student_list.students[i].surname,
                               student_list.students[i].class_name,
                               student_list.students[j].name,
                               student_list.students[j].surname,
                               student_list.students[j].class_name);
  }
 
  ClearStudents(&student_list);
  return 0;
}