Mega Code Archive
Qsort [array of pointers to structures]
<![CDATA[
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
struct node {
char *str;
};
/* compare function for qsort */
static int cmpr(const void *a, const void *b);
int main(void) {
struct node **strarray = NULL;
int i = 0, count = 0;
char line[1024];
while(fgets(line, 1024, stdin) != NULL) {
/* add ONE element to the array */
strarray = (struct node **)realloc(strarray, (count + 1) * sizeof(struct node *));
/* allocate memory for ONE `struct node` */
strarray[count] = (struct node *)malloc(sizeof(struct node));
/* copy the data into the new element (structure) */
strarray[count]->str = strdup(line);
count++;
}
/* before sorting ... */
printf("Before:\n");
for(i = 0; i < count; i++) {
printf("[%d]->str: %s", i, strarray[i]->str);
}
/* qsort array of structures */
qsort(strarray, count, sizeof(*strarray), cmpr);
/* after sorting ... */
printf("\n--\nAfter:\n");
for(i = 0; i < count; i++) {
printf("[%d]->str: %s", i, strarray[i]->str);
}
/* free all strarray elements */
for(i = 0; i < count; i++) {
free(strarray[i]->str);
free(strarray[i]);
i++;
}
free(strarray);
return 0;
}
/* compare function for qsort */
static int cmpr(const void *a, const void *b) {
struct node * const *one = a;
struct node * const *two = b;
return strcmp((*one)->str, (*two)->str);
}
]]>