Problem with file opening by C

[Ugurcan Sengit]

Hello , I'm new on programming and I'm trying to pass one more step to files. I wrote the following code and opened the " dosya.txt " file to true folder. At first I wrote it to G:\\dosya.txt , then I got null character as a return. After this I changed it to C:\\dosya.txt , now I got
" Unhandled exception at 0x5521e42e (msvcr100d.dll) in asd.c.exe: 0xC0000005: Access violation writing location 0xcccccccc. " error and I don't know how to solve it. I think I didn't do anything wrong but my code doesn't work. Can you help me to solve this ? Thanks a lot :)

#include <stdio.h>
#include <stdlib.h>
int main()
{
    int i,a[5];
    FILE *ptr;
    ptr = fopen("C:\\dosya.txt","r");
    if(ptr==NULL)
        printf("File does not exist !");
    for(i=0;i<5;i++,ptr++)
    {
        fscanf(ptr,"%d",a[i]);
        printf("%d\n",a[i]);
    }
}

[Alex Bránya]

Here is an answer:

//don't increase ptr manually, it's done by internal
for(i=0;i<5;i++,ptr++)
 
//this is the right format
for(i=0;i<5;i++)
 

[Ugurcan Sengit]

I just done what you've said but it still doesn't work. I got same error message :(

[Alex Bránya]

I have compiled after modification, anyway try this:
(I have compiled too, and it runs)

#include <stdio.h>
#include <stdlib.h>
  int main()
  {
       int i;
       int a[]={19,21,9,3,75};  //initialize array
       FILE *ptr;
       ptr = fopen("C:\\dosya.txt","w");
       if(ptr==NULL)
       printf("File does not exist !");
 
 
       for(i=0;i<5;i++) 
       {           
       fprintf(ptr,"%d",a[i]); //write to file
       }
 
    rewind (ptr);  //reset file pointer
 
       for(i=0;i<5;i++) 
       {
           fscanf(ptr,"%d",a[i]); //read from file
           printf("%d\n",a[i]);   
       }
 
         fclose (ptr);
 
 }