Thread: noobie binary questions

this is probably a really lame question for all you brainiacks
but thanks to assistance from people on this forum i've started
to experiment in accessing files in binary. But i dont understand
what the numbers are that i get from using fread(). What do these
long numbers represent??

for example if i use this code on a jpg file......

Code:

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


main()
{
    int r,i;                              /*r holds what i get from fread*/
    FILE *ptr;

    ptr=fopen("c:\\test.jpg","rb");
    
    if(ptr==0){
    printf("didnt work");
    getchar();}

    else
    printf("it worked fine\n\n");

    for (i=0;i<3;i++){

    while(fread(&r,sizeof(r),1,ptr)!=1)
         {
              printf("Write error occurred\n");
              getchar();
              exit(1);
          }
 
    printf("%i\n", r);
 }
    fclose(ptr);
    getchar();
    
    
    return 0;
}

.....i get -520103681
1179258880
16795209

what do these mean?? What are they?
And if i change the integer r to a long, printf will not display anything!
can anybody tell me why!?!

What did you think reading 3 integers from a jpeg file would do? It read some binary information from the header and stuffed it in an int. Probably nothing meaningful. %i is the integer formatting flag for printf, you need to add the length specifier l so %li or %ld.