void taksinomisi(){
int ye,mi,im,i,j,N;
float lo;
char s[15];

x=fopen("oikonomika.dat","rb+");
fseek(x,0,SEEK_END); //Paei to diktio sto telos gia na mporesei i ftell na exei swsto apotelesma
N=ftell(x)/sizeof(struct oikonomika);
//printf("To N einai %d",N);
for(i=0;i<N;i++)
      for(j=0;j<N-i-1;j++){
          fseek(x,j*sizeof(struct oikonomika),SEEK_SET);
          fread(&o,sizeof(struct oikonomika),1,x);
          fread(&o2,sizeof(struct oikonomika),1,x);
            //printf("%-2d:%-2d:%-2d      %-10s         %-4.2f\n",o.im,o.mi,o.ye,o.onoma,o.poso);
           // printf("%-2d:%-2d:%-2d      %-10s         %-4.2f\n",o2.im,o2.mi,o2.ye,o2.onoma,o2.poso);

          if(o.ye>o2.ye || (o.ye==o2.ye && o.mi>o2.mi) || (o.ye==o2.ye && o.mi==o2.mi && o.im>o2.im)){
             // printf("To o2.ye itan: %d\n",o2.ye);

              ye=o.ye;
              o.ye=o2.ye;
              o2.ye=ye;

              mi=o.mi;
              o.mi=o2.mi;
              o2.mi=mi;

              im=o.im;
              o.im=o2.im;
              o2.im=im;

              strcpy(s,o.onoma);
              strcpy(o.onoma,o2.onoma);
              strcpy(o2.onoma,s);

              lo=o.poso;
              o.poso=o2.poso;
              o2.poso=lo;

              fwrite(&o,sizeof(struct oikonomika),1,x);
              fwrite(&o2,sizeof(struct oikonomika),1,x);
          }

      }
}