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

#define N 5

struct Poleis {
	char kp[6];
	char po[20];
	int pl;
	char no[20];
};

struct IPoleis{
	char kp[6];
	int dief;
};


main() {
	struct Poleis pol;
	struct IPoleis *bpol;
	FILE *f;
	FILE *k;
	char oa[20]="Poleis.dat";
	char ob[20]="Poleis.ndx";
	int pl, m=0, i, j, tm, sinexeia;
	
	f=fopen(oa, "rb");

	if (!f) { 
		f=fopen(oa, "wb");
		k=fopen(ob, "wb");
		fclose(k);
		pl=0;
	}
	else {
		k=fopen(ob, "rb");
		fseek(k, 0, SEEK_END);
		pl=ftell(k) / sizeof(struct IPoleis);
		fclose(k);
		fseek(f, 0, SEEK_END);
	}

	m=pl;
	

	bpol = malloc( (pl+N) * sizeof(struct IPoleis));
	printf("\neisagwgi eggrafwn\n\n");
	do {
		printf("eisagwgi kp: ");
		scanf("%s", &pol.kp);
		printf("eisagwgi po: ");
		scanf("%s", &pol.po);
		printf("eisagwgi pl: ");
		scanf("%d", &pol.pl);
		printf("dwse to no: ");
		scanf("%s", &pol.no);
		

		fwrite(&pol, sizeof(struct Poleis), 1, f);
		strcpy(bpol[m].kp, pol.kp);
		bpol[m].dief = m;
		m++;
		
		printf("\nthelete nea eisagwgi? Eisagete 1 gia nai: ");
		scanf("%d", &sinexeia);



		if (sinexeia==1) 
			if (m == pl+N) {
				

				k=fopen(oa, "rb+");
				fseek(k, 0, SEEK_END);
	
				for (i=pl; i<pl+N; i++) 
					fwrite(&bpol[i], sizeof(struct IPoleis), 1, k);
				fclose(k);

				free(bpol);
				pl+=N;
				bpol = malloc( (pl+N) * sizeof(struct IPoleis));
			}
		
	} while ((sinexeia == 1) && (m < pl+N));
	
	

	fclose(f);

	k=fopen(ob, "rb+");
	fseek(k, 0, SEEK_END);

	for(i=pl;i<m;i++)
		fwrite(&bpol[i], sizeof(struct IPoleis), 1, k);

	fclose(k);
}