Question

C programming.

1.Create a program that does the following
- Creates three pointers, a character pointer professor, and two integer pointers student_ids, grades
- Using dynamic memory, use calloc to allocate 256 characters for the professor pointer
- Prompts the professor for their name, and the number of students to mark.
- Stores the professor’s name using the professor pointer and in an integer the number of students to mark.
- Using dynamic memory, use malloc to allocate memory for student_ids and grades to hold the number of students the professor needs to mark.
- The program does not need to do anything else, ensure that you free your memory before terminating.
- You will need to review the malloc, calloc, and sizeof documentation.

2. Building upon the previous questions you will create a marking system for professors at UOIT.
- Structs can be used the same as any other data type in C, instead of having two arrays for the grades and student ids create a struct called grade that contains two integers: student_id and mark.
- Create a function grade_students which takes the following arguments: a pointer to the grade struct called grades, and an integer num_students. The function returns void and does the following:
- Opens the file grades.txt in write mode
- Using the num_students parameter iterates through all of the grade structs pointed to by the grades parameter (remember arrays are pointers, you can treat pointers like arrays).
- For each grade structure adds the mark member of the struct to a variable called sum that holds the sum of all student’s grades.
- For each grade structure write to the file grades.txt the student id and the mark on a single line.

Answer 1

PLEASE REFER BELOW CODE

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

typedef struct grade
{
    int student_id;
    int mark;
}grade;

void grade_students(struct grade *grades, int num_students)
{
    FILE *fptr;
    int i,sum;
    fptr = fopen("grades.txt", "w");

    sum = 0;
    for(i = 0; i < num_students; i++)
    {
        sum += grades[i].mark;
        fprintf(fptr, "%d\t%d\n", grades[i].student_id,grades[i].mark);
    }
    fclose(fptr);
}

int main()
{
    int num_students;
    struct grade *g;
    char *professor;
    int *student_ids;
    int *grades;
    int i;
    professor = (char*)calloc(256, sizeof(char));

    printf("Enter Professor name : ");
    scanf("%[^\n]", professor);
    printf("Enter number of students to mark : ");
    scanf("%d", &num_students);
    // creating two arrays using malloc
    student_ids = (int*)malloc(sizeof(int) * num_students);
    grades = (int*)malloc(sizeof(int) * num_students);

    //b) //allocating array of struct for num of students
    g = (grade*)malloc(sizeof(grade) * num_students);
//asking user input
    for(i = 0; i < num_students; i++)
    {
        printf("Enter id and marks of %d student : ", (i+1));
        scanf("%d %d", &g[i].student_id,&g[i].mark);
    }
    grade_students(g, num_students); //calling function

    return 0;
}

PLEASE REFER BELOW OUTPUT

OUTPUT FILE grades.txt is

1   45
2   48
3   90
4   99