luc085.c

Metadata

• Author — Amit Dutta
• Last updated — 08 Feb 2026
• License — MIT License (See the LICENSE file for details)

Problem Statement

Problem Statement

Suppose a file contains student records (Name, Age). Write a program to read these records and display them in sorted order by name.

Source Code

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

struct student
{
    char name[40];
    int age;
};

void create_dummy_data();
int compare_names(const void *a, const void *b);

int main()
{
    FILE *fp;
    struct student s[100];
    int count = 0, i;

    // Create sample file for demonstration
    create_dummy_data();

    fp = fopen("students.dat", "rb");
    if (fp == NULL)
    {
        printf("Cannot open file!\n");
        exit(1);
    }

    // Read records into array
    while (fread(&s[count], sizeof(struct student), 1, fp) == 1)
    {
        count++;
    }
    fclose(fp);

    // Sort the array
    qsort(s, count, sizeof(struct student), compare_names);

    printf("--- Student List (Sorted by Name) ---\n");
    for (i = 0; i < count; i++)
    {
        printf("Name: %-20s Age: %d\n", s[i].name, s[i].age);
    }

    return 0;
}

int compare_names(const void *a, const void *b)
{
    return strcmp(((struct student *)a)->name, ((struct student *)b)->name);
}

void create_dummy_data()
{
    FILE *fp = fopen("students.dat", "wb");
    struct student data[] = {
        {"Zack", 20}, {"Alice", 19}, {"Bob", 21}, {"Charlie", 20}, {"Yasmine", 19}
    };
    if (fp)
    {
        fwrite(data, sizeof(struct student), 5, fp);
        fclose(fp);
    }
}