Thread: Sorting Alphabetically

>I have searched around on google but can't find anything of much help.
That's a bit odd. Sorting an array of structures based on a single field is a common question and has a common answer:

Code:

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

#define LENGTH(x) (sizeof x / sizeof *x)

struct test {
  char name[40];
  int age;
};

int cmp_name(const void *a, const void *b)
{
  const struct test *sa = a;
  const struct test *sb = b;

  return strcmp(sa->name, sb->name);
}

int cmp_age(const void *a, const void *b)
{
  const struct test *sa = a;
  const struct test *sb = b;

  if (sa->age < sb->age)
    return -1;
  else if (sa->age > sb->age)
    return +1;
  else
    return 0;
}

int main(void)
{
  struct test my_test[] = {
    {"Julienne", 21}, /* I wish ;) */
    {"Tom", 29},
    {"Generic Guy", 40},
    {"Generic Girl", 40},
    {"Other People", 33},
    {"Too lazy to think up another", 13},
  };
  int i;

  qsort(my_test, LENGTH(my_test), sizeof my_test[0], cmp_name);
  for (i = 0; i < LENGTH(my_test); i++)
    printf("%s -- %d\n", my_test[i].name, my_test[i].age);
  printf("\n");

  qsort(my_test, LENGTH(my_test), sizeof my_test[0], cmp_age);
  for (i = 0; i < LENGTH(my_test); i++)
    printf("%s -- %d\n", my_test[i].name, my_test[i].age);
  printf("\n");

  return 0;
}