Why do I get these warnings even though the headers are included?

Question

GCC is spitting warnings, which make no sense for me. I've the needed stdio library included. The execution of this program works as expected and I got 100% points on EDX too. Also what are these warnings about size 6 and size 5 ?

Code so far:

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

struct student {
      char name[50];
      int age;
      struct student *next;
};

struct student *createStudent(char studentName[50], int studentAge);
struct student * append(struct student * end, struct student * newStudptr);
void printStudents(struct student *start);
void copyStr(char [], char []);
/* add other prototypes here if needed*/

int main(void) {
    struct student *start, *newStudptr, *end, *tmp;
    int ageP, ageR, ageM;

    scanf("%d %d %d", &ageP, &ageR, &ageM);

    start = createStudent("Petra", ageP);
    end = start;

    newStudptr = createStudent("Remi", ageR);
    end = append(end, newStudptr);

    newStudptr = createStudent("Mike", ageM);
    end = append(end, newStudptr);

    printStudents(start);
    tmp = start->next;

    free(start);

    start = tmp;
    tmp = start->next;

    free(start);
    free(tmp);

    return 0;
}

struct student* createStudent(char studentName[50], int studentAge) {
    struct student* newStud;

    newStud = (struct student*) malloc(sizeof(struct student));

    copyStr(studentName, newStud->name);
    newStud->age = studentAge;
    newStud->next = NULL;

    return newStud;
}

struct student* append(struct student* end, struct student* newStudPtr) {
    end->next = newStudPtr;
    end = newStudPtr;

    return end;
}

void copyStr(char source[], char target[]) {
    int i = 0;

    while(source[i] != '\0') {
        target[i] = source[i];
        i++;
    }

    target[i] = '\0';
}

void printStudents(struct student* start) {
    struct student* ptr = start;

    while(ptr != NULL) {
        printf("%s is %d years old.\n", ptr->name, ptr->age);
        ptr = ptr->next;
    }
}

/* Place your function definitions here. Be sure to include the definitions for 
   createStudent() and append() as well as any other functions you created for 
   the previous tasks. */

The warnings:

:!gcc -Wall -std=c17 edx_PrintLinkedList.c -o bin/edx_PrintLinkedList                                                                                                                 
edx_PrintLinkedList.c: In function ‘main’:
edx_PrintLinkedList.c:22:13: warning: ‘createStudent’ accessing 50 bytes in a region of size 6 [-Wstringop-overflow=]
   22 |     start = createStudent("Petra", ageP);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
edx_PrintLinkedList.c:22:13: note: referencing argument 1 of type ‘char *’
edx_PrintLinkedList.c:45:17: note: in a call to function ‘createStudent’
   45 | struct student* createStudent(char studentName[50], int studentAge) {
      |                 ^~~~~~~~~~~~~
edx_PrintLinkedList.c:25:18: warning: ‘createStudent’ accessing 50 bytes in a region of size 5 [-Wstringop-overflow=]
   25 |     newStudptr = createStudent("Remi", ageR);
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
edx_PrintLinkedList.c:25:18: note: referencing argument 1 of type ‘char *’
edx_PrintLinkedList.c:45:17: note: in a call to function ‘createStudent’
   45 | struct student* createStudent(char studentName[50], int studentAge) {
      |                 ^~~~~~~~~~~~~
edx_PrintLinkedList.c:28:18: warning: ‘createStudent’ accessing 50 bytes in a region of size 5 [-Wstringop-overflow=]
   28 |     newStudptr = createStudent("Mike", ageM);
      |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
edx_PrintLinkedList.c:28:18: note: referencing argument 1 of type ‘char *’
edx_PrintLinkedList.c:45:17: note: in a call to function ‘createStudent’
   45 | struct student* createStudent(char studentName[50], int studentAge) {

Answer 1

we dont know which lines you can change or not

But gcc is complainng about this

you say

   struct student* createStudent(char studentName[50], int studentAge)

but then you do

   start = createStudent("Petra", ageP);

which is trying to invoke it as a

  struct student* createStudent(char studentName[6], int studentAge)

function

can you do

  struct student* createStudent(char studentName[], int studentAge)

That will work

edit

---

YOu can also fix it like this

  char name[50];
  ....
  strcpy(name, "Petra");
  start = createStudent(name, ageP);