Thread: Using qsort to read from a file

Hello all,

Trying to understand how to use qsort with arrays and functions reading from a file (bin). I think I have the general idea of how qsort works, but when it comes to reading from a .bin file I am completely lost! My intended output is to make it so so that it comes out in order of destination airport code, with the date and time formatted into a human-readable string. I do not understand how to convert the timestamp using time.h, but I am not worried about that for now.

Code:

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




                typedef struct MyStruct_struct{
                char FlightNum[7];
                char OriginAirportCode[5]; 
                char DestAirportCode[5];
                unsigned timeStamp;
            } MyStruct;
            
            
            MyStruct Order[5000];
            
            int compare (const void *v1, const void *v2) 
            {
           
            const MyStruct *ia = (MyStruct *)v1;
            const MyStruct *ib = (MyStruct *)v2;
                int result=0;
                if (ia->OriginAirportCode < ia->OriginAirportCode)
                    return -1;
                else if (ia->OriginAirportCode > ia->OriginAirportCode)
                    return +1;
                else
                    return 0;
                
    
             }
            
            int main(){
            int i;
              
                
                     
                 FILE * bin;
                 MyStruct myStruct;
                 
                 bin = fopen("acars.bin", "rb");
                 qsort(Order, 5000, sizeof( MyStruct), compare);
                 for (i = 0; i < 300; i++){


                 printf("%i) %s, %s, %s\n", i, Order[i].FlightNum, Order[i].OriginAirportCode, Order[i].DestAirportCode);
                 }
                
            
               
                
                
                fclose(bin);
                
                return 0;
            }