Logical error in code - error-handling

Question

Code that I am supposed to fill out which was easy enough.
#define MAX_NAME_LEN 128
typedef struct {
char name[MAX_NAME_LEN];
unsigned long sid;
} Student;
/* return the name of student s */
const char* getName(const Student* s) {
return s->name;
}
/* set the name of student s */
void setName(Student* s, const char* name) {
/* fill me in */
}/* return the SID of student s */
unsigned long getStudentID(const Student* s) {
/* fill me in */
}
/* set the SID of student s */
void setStudentID(Student* s, unsigned long sid) {
/* fill me in */
}
However it says what is the logical error in the following function?
Student* makeDefault(void) {
Student s;
setName(&s, "John");
setStudentID(&s, 12345678);
return &s;
}
I do not see any problems. I tested it. It works fine.
Is it because this should probably be a void function and does not need to be returning anything?

Answer 1

You can't return a pointer to a locally declared variable (Student s). The variable "s" will disappear (become garbage) after the return.
Instead, you need to allocate a student first.
You should probably do this:
void makeDefault(Student* pS) {
setName( pS, "John");
setStudentID( pS, 12345678);
}
And then let the calling application allocate the student.