Pomoc oko datoteka - pocetnik - hitno !!!

Code:


FILE *fajl;

if ((fajl = fopen("izraz.txt","r+")) == NULL)
{
FILE *fajl = fopen("izraz.txt","w+"));
}
else
{
FILE *fajl = fopen("izraz.txt","r+"));
}

Code:
FILE *fajl = fopen("izraz.txt","w"));

Code:
FILE *fajl;

if ((fajl = fopen("izraz.txt","r+")) == NULL)
{
FILE *fajl = fopen("izraz.txt","w+"));
}
else
{
FILE *fajl = fopen("izraz.txt","r+"));
}

Code:
FILE *fajl;

if ((fajl = fopen("izraz.txt","r+")) == NULL)
{
fajl = fopen("izraz.txt","w+"));
}
else
{
fajl = fopen("izraz.txt","r+"));
}

Code:
#include <stdio.h>
main()
{ 

   FILE *fdat;

   if ((fdat=fopen("fajl.txt","w")) ==NULL)
      printf("\n Greška pri otvaranju datoteke") ;
   else
      {
            // ostatak koda za citanje iz datoteke (fread(), fscanf(), ...
      }
}