C - initialize array of structs
This is incorrect:
student** students = malloc(sizeof(student));
You do not want a **
. You want a *
and enough space for how ever many students you need
student *students = malloc(numStudents * sizeof *students); // or sizeof (student)
for (x = 0; x < numStudents; x++)
{
students[x].firstName = "John"; /* or malloc and strcpy */
students[x].lastName = "Smith"; /* or malloc and strcpy */
students[x].day = 1;
students[x].month = 12;
students[x].year = 1983;
}
If you still want to use the code in your "//add struct" section, you'll need to change the line:
student* newStudent = {"john", "smith", 1, 12, 1983};
to
student newStudent = {"john", "smith", 1, 12, 1983};
You were getting "initialization from incompatible pointer type" because you were attempting to initialize a pointer to student
with an object of type student
.
Unrelated to the compiler warnings, but your initial malloc is wrong; you want:
malloc(sizeof(student *)* numStudents)
To allocate room for a total of 'numStudents' pointers to a student. The line:
students[x] = (struct student*)malloc(sizeof(student));
Should be:
students[x] = (student*)malloc(sizeof(student));
There's no such thing as 'struct student'. You've declared an unnamed struct and typedef'd it to 'student'. Compare and contrast with:
struct student
{
char* firstName;
char* lastName;
int day;
int month;
int year;
};
Which would create a 'struct student' type but require you (in C) to explicitly refer to struct student rather than merely student elsewhere. This rule is changed for C++, so your compiler may be a bit fuzzy about it.
As for:
student* newStudent = {"john", "smith", 1, 12, 1983};
That should be:
student newStudent = {"john", "smith", 1, 12, 1983};
As the curly brace syntax is a direct literal, not something somewhere else that you need to point to.
EDIT: on reflection, I think aaa may have taken more of an overview of this than I have. Is it possible that you're inadvertently using an extra level of pointer dereference everywhere? So you'd want:
student* students = malloc(sizeof(student) * numStudents);
/* no need for this stuff: */
/*int x;
for(x = 0; x < numStudents; x++)
{
//here I get: "assignment from incompatible pointer type"
students[x] = (struct student*)malloc(sizeof(student));
}*/
int arrayIndex = 0;
And:
student newStudent = {"john", "smith", 1, 12, 1983};
//add it to the array
students[arrayIndex] = newStudent;
arrayIndex++;
Subject the array not being used outside of scope of newStudent. Otherwise copying the pointers to strings is incorrect.