Thread: Can't figure out how to swap

With this program, I'm trying to open a file that contains a list of people's names, birth dates, grade numbers, and SSN. I can get it to read the pieces from the file and print them but I'm trying to get it in alphabetical order with a selection sort and it will not swap them. :/. plz help. and btw, theres certain parts in here that won't make sense why i have them in there, but that's because theres much more to the program to be done. thank you for your time

Code:

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

#define MAX 20
#define SIZE 5

//date structure
typedef struct
{ 
   char month[MAX];
   int date;
   int year;
} DATE;

//student structure
typedef struct
{
   char fName[MAX];
   char lName[MAX];
   int gLevel;
   char sNumber[MAX];
   DATE bDate;
} STUDENT;

//functions
void fill(STUDENT identity[], FILE* fpIn, FILE* fpOut);
void printArr(STUDENT identity[]);
bool openFiles(FILE **pFPIn, FILE **pFPOut);
void prt(STUDENT identity);
void sort(STUDENT identity[]);
void swap(STUDENT *pN1, STUDENT *pN2);

//main function
int main(int argc, char* argv[])
{
   STUDENT identity[SIZE];
 
   FILE *fPIn, *fPOut;
   int i;
   if (openFiles(&fPIn, &fPOut))
      {
         fill(identity, fPIn, fPOut);
         printf("\nCreated by _______");
         printf("\n\n%26s %10s %15s %17s", "Name", "Level", 
                "SSN", "Birthdate");
         printf("\n%26s %10s %15s %17s", "----", "-----", 
                "---", "---------");
         printArr(identity);    //prints the unsorted array
         sort(identity);        //sorts the array
         printArr(identity);    //prints the sorted array 

       }
  
       
   fclose(fPIn);
   fclose(fPOut);
  
   return 0;
}

//generate function
void fill(STUDENT identity[], FILE* fPIn, FILE* fPOut)
{
   int i;
   
   //for loop
   for (i = 0; i < SIZE; i++)
      {
         fscanf(fPIn, "%s%s%d%s%s%d%d", 
             identity[i].fName, identity[i].lName,
             &identity[i].gLevel, identity[i].sNumber,
             &identity[i].bDate.month, &identity[i].bDate.date,
             &identity[i].bDate.year);
      }
}

//print function into array of structures
void printArr(STUDENT identity[])
{
   int i;
   
   //for loop
   for (i = 0; i < SIZE; i++)
     {
       printf("\n");
       prt(identity[i]);
     
     }
   printf("\n\n");
}

//opens the files
bool openFiles(FILE **pFPIn, FILE **pFPOut)
{
   bool success = false;   

   if ((*pFPIn = fopen("t1", "r")) != NULL)
   {
      if ((*pFPOut = fopen("t1.out", "w")) != NULL)
         success = true;
      else
         printf("\nUnable to open \"t1.out\" for writing.\n\n");
   }
   else
      printf("\nUnable to open \"t1.txt\" for reading.\n\n");
   
   return success;
}
//prints the function   
void prt(STUDENT identity)
{
   
    printf("%17s %8s %10d %15s %9s %2d %d%", identity.fName, 
         identity.lName, 
         identity.gLevel,
         identity.sNumber,
         identity.bDate.month,
         identity.bDate.date,
         identity.bDate.year);
}

//selection sort function
void sort(STUDENT identity[])
{

   int pass, min, trav;
   
   for (pass = 0; pass < SIZE - 1; pass++)
    {
      for (min = pass, trav = pass + 1; trav < SIZE; trav++)
         { 
            if (identity[trav].lName < identity[min].lName)
               {
                  min = trav;
               }
            trav++;
                   
         } 
      swap(&identity[pass], &identity[min]);
      pass++;
    } 
}

//swap function
void swap(STUDENT *pN1, STUDENT *pN2)
{
   char temp;
   
   temp = pN1;
   pN1 = pN2;
   pN2 = temp;
}

The current swap function is the only way that I have done that would compile, it gave me warning messages however.

this is what i'm getting it to print

Code:

$ ./a.out

Created by 

                      Name      Level             SSN         Birthdate
                      ----      -----             ---         ---------
            Peter  Griffin          1     111-11-1111       May  9 1965
             Lois  Griffin          3     234-33-2345     April  2 1966
            Glenn Quagmire          7     555-41-2143   January 10 1965
              Tom   Tucker          2     999-99-9999      July  4 1970
             Adam     West         10     444-22-3434  November  4 1960


            Peter  Griffin          1     111-11-1111       May  9 1965
             Lois  Griffin          3     234-33-2345     April  2 1966
            Glenn Quagmire          7     555-41-2143   January 10 1965
              Tom   Tucker          2     999-99-9999      July  4 1970
             Adam     West         10     444-22-3434  November  4 1960

oops, that first one i didnt mean to send. i had clicked on preview and went back to edit i thought. its early. sorry :/

well after a few replies on different threads by many different people. i've noticed that a lot ask for more code posted, so i thought id just cancel out that, but i apologize if it bothers you :/

and i've gotten it to give no warnings now, but it is still not swapping. baby steps

[CODE]
void swap(STUDENT *pN1, STUDENT *pN2)
{
STUDENT *temp[MAX];

*temp = pN1;
pN1 = pN2;
pN2 = *temp;
}
/CODE]

alright, i changed it from an array to just one 1 temp variable. i then changed them from pointers to just objects. i then had to change the & symbols from the calling function. it compiles with no warnings but still no swapping. and i also realized that by last name, the names i had in the file were already in order except for the two griffins. lawlz. so i switched adam wests place to the top to make it simple.

alrighty, its back to pointers. again it compiles but still no swaps.

Code:

void swap(STUDENT *pN1, STUDENT *pN2)
{
   STUDENT temp;
          
   temp = *pN1;
   *pN1 = *pN2;
   *pN2 = temp;
}