SORT NAMES IN ALPHABETICAL ORDER USING POINTERS

SORT NAMES IN ALPHABETICAL ORDER USING POINTERS


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

#define N 5
#define MAX_STRLEN 256
#define MAX_NAMELEN 128

typedef struct {
  char *first;
  char *last;
} Name;

void sort(Name *a, int n);
Name *nameArray;

int main(int argc, char *argv[]) {
  int i;
  char line[MAX_STRLEN],*p;

  nameArray = (Name *)calloc(N,sizeof(Name));
  printf("\nEnter %d names (First Last), one per line:\n",N);
  for (i = 0; i < N; i++) {
    printf("> ");
    fgets(line,MAX_STRLEN,stdin);
    *(strchr(line,'\n')) = '\0';
    if (strlen(line) > 0) {
      /*
       * Could use some more logic here to verify input.
       * This will work for : First Last
       */
      p = strchr(line,' '); *p++ = '\0';
      nameArray[i].first = (char *)malloc(strlen(line));
      nameArray[i].last = (char *)malloc(strlen(p));
      strcpy(nameArray[i].first,line);
      strcpy(nameArray[i].last,p);
    }
  }
  sort(nameArray,N);
  printf("\nSorted:\n");
  for (i = 0; i < N; i++) {
    printf("%s, %s\n",
       nameArray[i].last, nameArray[i].first);
    free(nameArray[i].first);
    free(nameArray[i].last);
  }
  free(nameArray);

  return 0;
}

/* selection sort */
void sort(Name *a, int n) {
  int min,i,j;
  Name t;

  for (i = 0; i < n; i++) {
    min = i;
    for (j = i+1; j < n; j++) {
      if (strcmp(a[j].last,a[min].last) < 0) min = j;
    }
    t = a[min];
    a[min] = a[i];
    a[i] = t;
  }
}