Structure

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

struct student
{
    char name[100];
    int roll;
    int marks;
};
struct student ar[500];

int main()
{
    int t, i = 0, j, k, l, a, b, c, d, x, y, z, n;
    char str[1000], str2[1000], *ptr;

    freopen("input.txt", "r", stdin);
    for (; ;)
    {
        gets(str);
        if (feof(stdin)) break;
        l = 0, ptr = strtok(str, " ");
        while(ptr != 0)
        {
            if (l == 0) strcpy(ar[i].name, ptr);
            if (l == 1) ar[i].roll = atoi(ptr);
            if (l == 2) ar[i].marks = atoi(ptr);
            l++;
            ptr = strtok(0, " ");
        }
        i++;
    }

    for (l = 0; l < i; l++) printf("%10s %10d %10d\n", ar[l].name, ar[l].roll, ar[l].marks);
    return 0;
}