model 2

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

typedef struct {
    int nr;
    char nume[30];
    int grupa;
    int pp;
    int pt[10];
    int pe;
    int is;
}Student;

int nrart(FILE *f, int l) {
    long p;
    int n;

    p = ftell(f);
    fseek(f, 0, 2);
    n = ftell(f)/l;
    fseek(f, p, 0);

    return n;
}

void BinInText(char *numeBin, char *numeTxt, Student s) {
    FILE *f, *g;
    int i;

    f = fopen(numeBin, "rb");
    g = fopen(numeTxt, "w");

    fprintf(g, "Nr. Nume %30s Grupa Pct proba Pct teme %20s Pct examen\n", " ", " ");
    fread(&s, sizeof(Student), 1, f);
    while(!feof(f)) {
        if(s.is == 1) {
            fprintf(g, "%3d %6s %30d %10d", s.nr, s.nume, s.grupa, s.pp);
            for(i = 0; i < 10; i++)
                fprintf(g, " %d ", s.pt[i]);
            fprintf(g, " %d\n", s.pe);
        }
        fread(&s, sizeof(Student), 1, f);
    }
    fclose(f);
    fclose(g);
}

int main() {
    Student s;
    FILE *f;
    char nume[20], numetxt[20];
    int nr, i;
    int length;

    printf("Fisier: "); gets(nume); fflush(stdin);
    printf("Fisier txt: "); gets(numetxt); fflush(stdin);
    f = fopen(nume, "wb");
    if(!f) printf("Fisierul nu s-a deschis!");
    else {
        printf("Nr. mat: ");
        scanf("%d", &nr);
        while(!feof(stdin)) {
            if(nr >= nrart(f, sizeof(Student))) {
                fseek(f, 0, 2);
                s.is = 0;
                for(i = nrart(f, sizeof(Student)); i <= nr; i++)
                    fwrite(&s, sizeof(Student), 1, f);
            }
            fseek(f, nr*sizeof(Student), 0);
            fread(&s, sizeof(Student), 1, f);
            if(s.is == 1) printf("Duplicat!");
            else {
                s.nr = nr;
                fflush(stdin);
                printf("Nume: "); gets(s.nume);
                length = strlen(s.nume);
                if(s.nume[length-1] == '\n') s.nume[length-1] = '\0';
                printf("Grupa: "); scanf("%d", &s.grupa);
                printf("Pct prb: "); scanf("%d", &s.pp);
                for(i = 0; i < 10; i++) {
                    printf("Tema %d: ", i+1);
                    scanf("%d", &s.pt[i]);
                }
                printf("Pct exam: "); scanf("%d", &s.pe);
                s.is = 1;
                fseek(f, nr*sizeof(Student), 0);
                fwrite(&s, sizeof(Student), 1, f);
            }
            printf("Nr. mat: "); scanf("%d", &nr);
        }
        fclose(f);
        BinInText(nume, numetxt, s);
    }

}