Linked List

[mystic bay]

I want to add a new value to my linked list, through the console but the last name wont print.

[tiny breach]

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[mystic bay]

!f

[tiny breach]

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
  char first_name[20];
  char last_name[20];
  int math_grade;
  int german_grade;
  int english_grade;
  struct pupils* next;
} pupils;

pupils* pupil;  // change while the programm is running
pupils* head;   // doesnt change --> is the head of the list

void print() {
  pupil = head;
  while (pupil != NULL) {
    printf("%s %s %d %d %d\n", pupil->first_name, pupil->last_name,
           pupil->math_grade, pupil->german_grade, pupil->english_grade);
    pupil = pupil->next;
  }
  printf("---------\n");
}

void create_head(char first_name_[20],
                 char last_name_[20],
                 int mathe_grade_,
                 int german_grade_,
                 int english_grade_) {
  pupils* temp = malloc(sizeof *temp);
  strcpy(temp->first_name, first_name_);
  strcpy(temp->last_name, last_name_);
  temp->math_grade = mathe_grade_;
  temp->german_grade = german_grade_;
  temp->english_grade = english_grade_;

  temp->next = NULL;

  pupil = temp;
  head = temp;
}
void add_pupil(char new_first_name[20],
               char new_last_name[20],
               int new_mathe_grade,
               int new_german_grade,
               int new_english_grade) {
  pupils* new = malloc(sizeof(*new));
  strcpy(new->first_name, new_first_name);
  strcpy(new->last_name, new_last_name);
  new->math_grade = new_mathe_grade;
  new->german_grade = new_german_grade;
  new->english_grade = new_english_grade;
  new->next = NULL;

  pupil = head;

  while (pupil != NULL) {
    if (pupil->next == NULL) {
      pupil->next = new;
      break;
    } else {
      pupil = pupil->next;
    }
    pupil->next = new;
  }
}

Monke

[mystic bay]

!f

[tiny breach]

int main() {
  int selection = 0, mathe_grade, german_grade, english_grade;
  char first_name[20];
  char last_name[20];
  char input;

  create_head("Ralph", "Reichts", 1, 3, 5);

  printf("What do you want to do?\n");
  printf("0 - Close program\n");
  printf("1 - Add a new pupil\n");
  scanf("%d", &selection);

  switch (selection) {
    case 0:
      return 0;
    case 1:
      printf("Insert the first name of the pupil.\n");
      scanf("%s", &first_name);
      printf("Insert the last name of the pupil\n");
      scanf("%s", &last_name);

      printf(
          "Do you got a math, german and english grade for the pupil?(y/n)\n");
      scanf("%s", &input);
      if (input == 'y' || input == 'Y') {
        printf("Plese insert the math grade of the pupil.\n");
        scanf("%d", &mathe_grade);
        printf("Plese insert the german grade of the pupil.\n");
        scanf("%d", &german_grade);
        printf("Plese insert the english grade of the pupil.\n");
        scanf("%d", &english_grade);

        add_pupil(first_name, last_name, mathe_grade, german_grade,
                  english_grade);
      } else if (input == 'n' || input == 'N') {
        add_pupil(first_name, last_name, 0, 0, 0);
      } else {
        printf(
            "Your input was not accepted by the System, the programm will shut "
            "down.\n");
        return 0;
      }
  }
  print();
  free(pupil);
  return 0;
}

Monke

[visual current]

The while loop in add_pupil seems wrong

I don't think you should have c pupil->next = new
outside of the if statement

It traverses the list and always sets the next pointer to be the new node - which you only want to do when you've reached the end of the list

[mystic bay]

thank you, but the problem is still there

[visual current]

Also with the scanf for the first and last name, it shoudn't be scanf("%s", &first_name) just scanf("%s", first_name)

same for last_name

[mystic bay]

okay, but the last name still wont print

[visual current]

Oh and it looks like your typedef is wrong

In your struct you use struct pupils, but you never declare this as your struct is anonymous

Instead I think you want something like:

typedef struct pupils pupils;
struct pupils {
  char first_name[20];
  char last_name[20];
  int math_grade;
  int german_grade;
  int english_grade;
  pupils* next;
};

[tiny breach]

@mystic bay Has your question been resolved? If so, type !solved :)

[hallow bear]

I agree with JamesZ suggestions. If you use &first_name or &last_name, make it &first_name[0] and &last_name[0] otherwise just use the character array name first_name, last_name as suggested by JameZ.

For your create_head function, I would change like this:

void create_head(char *first_name_,
                 char *last_name_,

WIth these changes:

$ ./a.out
What do you want to do?
0 - Close program
1 - Add a new pupil
1
Insert the first name of the pupil.
Joe
Insert the last name of the pupil
Blow
Do you got a math, german and english grade for the pupil?(y/n)
y
Plese insert the math grade of the pupil.
4
Plese insert the german grade of the pupil.
3
Plese insert the english grade of the pupil.
2
Ralph Reichts 1 3 5
Joe Blow 4 3 2