96 students record; pass marks

Logic.

1. Open ioe.txt in write mode; read name, roll number and marks of 96 students in a loop and write each record with fprintf().
2. Close the file, reopen it in read mode.
3. Read the records back with fscanf() until it no longer returns 3, and print the roll number and name of those with marks >= 40.

#include <stdio.h>
#ifndef N
#define N 96
#endif

int main(void)
{
    FILE *fp;
    char name[30];
    int roll;
    float marks;

    fp = fopen("ioe.txt", "w");
    if (fp == NULL) {
        printf("Cannot create ioe.txt\n");
        return 1;
    }
    for (int i = 1; i <= N; i++) {
        printf("Student %d (name roll marks): ", i);
        scanf("%29s %d %f", name, &roll, &marks);
        fprintf(fp, "%s %d %.1f\n", name, roll, marks);
    }
    fclose(fp);

    fp = fopen("ioe.txt", "r");
    if (fp == NULL) {
        printf("Cannot open ioe.txt\n");
        return 1;
    }
    printf("\nStudents with marks >= 40\n%-6s %s\n", "Roll", "Name");
    while (fscanf(fp, "%29s %d %f", name, &roll, &marks) == 3)
        if (marks >= 40)
            printf("%-6d %s\n", roll, name);
    fclose(fp);
    return 0;
}

Sample run (N reduced to 3 with -DN=3 for the test; the real program uses 96)

Input (entered one after another): Ram 1 65 Sita 2 32 Hari 3 40

Students with marks >= 40
Roll   Name
1      Ram
3      Hari