My code is as follows:

    #define MAX_ELEMENTS 100
    #define MAXIMUM_LENGTH 50

typedef struct {
    char teacher;
    int id;
    char day[MAXIMUM_LENGTH];
    char startingTime[MAXIMUM_LENGTH];
    char endingTime[MAXIMUM_LENGTH];
} officehours;

officehours list[MAX_ELEMENTS]; 
int c = 0;
char filenamep[20];


void store_office_hour(char teacher, officehours data[], int count, char* filename) {
    FILE* fp = fopen(filename, "w");
    if (fp == NULL) {
        printf("ERROR in %s: Unable to open file.n", __func__);
        return;
    }

    for (int i = 0; i < count; i++) {
        fprintf(fp, "%d %s %s %sn", data[i].id, data[i].day, data[i].startingTime, data[i].endingTime);
        fprintf(stderr, "DEBUG: %d %s %s %s n", data[i].id, data[i].day, data[i].startingTime, data[i].endingTime);
       
  
    }

    fclose(fp);
}

  void insert_office_hour(char teacher) {
      
      filenamep[0] = teacher;
      filenamep[1] = '';
      strcat(filenamep, ".txt");


      FILE* fp = fopen(filenamep, "r");
      if (fp != NULL) { 
          c = 0;
          while (fscanf(fp, "%d %s %s %s", &list[c].id, list[c].day, list[c].startingTime, list[c].endingTime) == 4) {
              c++;
          }
          fclose(fp);
      }

      if (c >= MAX_ELEMENTS) {
          printf("ERROR in %s: Database is full.n", __func__);
          return;
      }

      officehours input;
      getchar();  
      printf("ttEnter identification number: ");
      scanf("%d", &input.id);
      getchar(); 

      printf("ttEnter a day: ");
      read_line(input.day, MAXIMUM_LENGTH);
 
      printf("ttEnter starting hour: ");
      read_line(input.startingTime, MAXIMUM_LENGTH);


      printf("ttEnter ending hour: ");
      read_line(input.endingTime, MAXIMUM_LENGTH);



      if (find_office_hour(list, c, input.id) != -1) {
          printf("This office hour already exists.n");
          return;
      }

      list[c++] = input;


      store_office_hour(teacher, list, c, filenamep);
  }

int read_line(char str[], int n) {
    int ch, i = 0;

    while (isspace(ch = getchar()));

   
    while (ch != 'n') {
        if (i < n - 1) 
            str[i++] = ch;
        ch = getchar();
    }
    str[i] = ''; 
    return i;
}

When inserting the office hours, the end time of the others is not printed to the file except for the last entered office hour.
When I write another code with the same logic, it writes to the file properly, but not in this project. I tried using getchar() but it did not solve my problem. I think the problem is directly in the store_office_hours function, but I can’t understand what it is caused by.

For example, when I expect the office hours to be written like this:

1 Monday 2 p.m. 3 p.m.
2 Friday 4 p.m. 7 p.m.
3 Thursday 5 p.m. 9 p.m.

the data is written to the file like this:

1 Monday 2 p.m.
2 Friday 4 p.m.
3 Thursday 5 p.m. 9 p.m.