如何仅使用指针访问结构数组

Question

I am trying to access the students array of structs and modify a "Student" at a given index (using a for loop).

However, I am trying to access it using only a pointer, not like this:
students[currStudent].theory = thoeryGrade;

But something along the lines of:
*(studentPtr + currStudent).practical = practicalGrade;
Note: The above line doesn't compile.

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

typedef struct Student
{
    double theory;
    double practical;
} Student;

int main()
{
    Student students[50];
    const int numStudents;
    int thoeryGrade, practicalGrade = 0;
    Student *studentPtr = students;

    printf("Enter number of students: ");
    scanf("%d", &numStudents);

    while (1)
    {
        for (int currStudent = 0; currStudent < numStudents; currStudent++)
        {
            printf("Enter theory average of student %d: ", (currStudent + 1));
            scanf("%d", &thoeryGrade);

            printf("Enter practical average of student %d: ", (currStudent + 1));
            scanf("%d", &practicalGrade);

            students[currStudent].theory = thoeryGrade;
            *(studentPtr + currStudent).practical = practicalGrade;
            printf("\n");
        }
        for (int currStudent = 0; currStudent < numStudents; currStudent++)
        {
            printf("Student # %d -> Theory: %.2f", (currStudent + 1), students[currStudent].theory);
            printf("\n");
            printf("Student # %d -> Practical %.2f", (currStudent + 1), students[currStudent].practical);
            printf("\n\n");
        }
    }

    return 0;
}

Answer 1

The . operator has higher precedence than * (dereference), so you need to enclose the expression *(studentPtr + currStudent) in brackets.

(*(studentPtr + currStudent)).practical = practicalGrade;

Alternatively, use the -> operator to directly access a member on the pointer.

(studentPtr + currStudent)->practical = practicalGrade;

Answer 2

This code has issues.

You must be ignoring compiler warnings about const in the declaration of const int numstudents .

Why does the scanf() accept integers, then store the pair into doubles?

It may be safe(?) to disregard the 0th element of the array, and make the loops for input and printing:

for (int currStudent = 1; currStudent <= numStudents; currStudent++)

Then you wouldn't need the currStudent+1 excess baggage.

The easiest way to condense the code is to use a temporary pointer inside the loop that points to the current student (array element).

for (int currStudent = 1; currStudent <= numStudents; currStudent++) {
    Student *pCur = &students[ currStudent ];

Then you can use pCur->theory and pCur->practical to copy or print.

Finally, "student" appears as all-or-part-of a datatype, an array name, a loop counter and text in a string. Perhaps the datatype could be renamed 'record' and the loop counter 'index'.