CODEWITHSUNDEEP
cbubble-sort
thewhiteknifer
thewhiteknifer

Reputation: 39

having trouble with bubble sort

i need to sort flights in a program

H100.15005 SAT HOU 08:00 4 65.00   
H111.15009 SAT HOU 17:00 10 65.00

im using bubble sort to make them in descending order for flight number my current program is 

void sortFlights(Flight flightM[], int iFlightCnt)
{
Flight temp;
int i, j, bChange = 1;
for (i = 0; i < (iFlightCnt - 1) && bChange == 1; i++)
{
    bChange = 0;
    for (j = 0; j < (iFlightCnt - i - 1); j++)
    {
        if (strcmp(flightM[i + 1].szFlightId, flightM[i].szFlightId) < 0)
        {
            temp = flightM[i];
            flightM[i] = flightM[i + 1];
            flightM[i + 1] = (Flight)temp;
            bChange = 1;
        }
    }
    }
}

currently the flights are not sorting. ive rechecked the for loops but cant figure it out

Upvotes: 1

Views: 70

Answers (1)

amdixon
amdixon

Reputation: 3833

problems

  • strcmp comparison direction
  • index referencing with stcmp and inner loop ( need to reference j+1 and j not i.. )

adjusted code

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

/* stub structure to replicate problem */
typedef struct
{
  char szFlightId[11];
}Flight;

void sortFlights(Flight flightM[], int iFlightCnt)
{
  Flight temp;
  int i, j, bChange = 1;
  for (i = 0; i < (iFlightCnt - 1) && bChange == 1; i++)
  {
    bChange = 0;
    for (j = 0; j < (iFlightCnt - i - 1); j++)
    {
      if (strcmp(flightM[j + 1].szFlightId, flightM[j].szFlightId) > 0) 
         /* change: reference j+1, 
                    direction of strcmp comparison for desired sort order */
      {
        temp = flightM[j];
        flightM[j] = flightM[j + 1];    /* change: reference j+1 */
        flightM[j + 1] = (Flight)temp;  /* change: reference j+1 */
        bChange = 1;
      }
    }
  }
}

/* convenience output function */
void printFlights(Flight *flightM, int iFlightCnt)
{
  int index;
  for(index = 0; index < iFlightCnt; index++)
  {
    printf("%d: %s\n", index, flightM[index].szFlightId);
  }
}

int main(void)
{
  Flight flightM[2];
  sprintf(flightM[0].szFlightId, "H100.15005");
  sprintf(flightM[1].szFlightId, "H100.15009");
  printf("==== input  ====\n");
  printFlights(flightM, 2);
  sortFlights(flightM, 2);
  printf("\n");
  printf("==== output ====\n");
  printFlights(flightM, 2);
  return 0;
}

output

$ ./sort_flights 
==== input  ====
0: H100.15005
1: H100.15009

==== output ====
0: H100.15009
1: H100.15005

reference

Upvotes: 1

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