include stdio include conio include stdlib include time define ERROR_O

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

#define ERROR_OPEN_FILE -3

void main() {
    FILE *iofile = NULL;
     FILE *iofile1 = NULL;
    unsigned counter = 0;
    int num,num1;
    int yn;
num=rand()%10;
    iofile = fopen("numbers.bin", "w+b");
    if (iofile == NULL) {
        printf("Error opening file");
        getch();
        exit(ERROR_OPEN_FILE);
    }

    iofile1= fopen("by4.bin", "w+b");
    if (iofile == NULL) {
        printf("Error opening file");
        getch();
        exit(ERROR_OPEN_FILE);
    }

    //fwrite(&counter, sizeof(int), 1, iofile);
    do {
        printf("enter new number? [1 - yes, 2 - no]");
        scanf("%d", &yn);
        if (yn == 1) {
            //scanf("%d", &num);
            num=rand()%10;
            fwrite(&num, sizeof(int), 1, iofile);
            counter++;
        } else {
            rewind(iofile);
            //fwrite(&counter, sizeof(int), 1, iofile);
            break;
        }
    } while(1);

int i,j,b;
    for (i = 0; i < counter; i++) {

        fread(&num, sizeof(int), 1, iofile);
        //printf("%d\n", num);
if ((i+1)%5!=0){
               printf("%d\n", num);
               fwrite(&num, sizeof(int), 1, iofile1);
               b++;
            }
    }
int counter1;
rewind(iofile1);
    for (j = 0; j < b; j++) {

        fread(&num1, sizeof(int), 1, iofile1);

        printf("%d\n", num1);
    }
    fclose(iofile);
    fclose(iofile1);
    getch();
}