count number of chars in a string and display by rank

countchars.c

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

int** count_chars(char *s)
{
	int **counts = (int**)malloc(256 * sizeof(int) * sizeof(char));
	int i;
	for(i = 0; i < 256; i++)
	{
		counts[i] = (int*)malloc(sizeof(int)*2);
		counts[i][0] = i;
		counts[i][1] = 0;
	}
	while(*s)
	{
		counts[(int)*s][1] += 1;
		s++;
	}
	return counts;
}

int int_pair_asc(const void *a, const void *b){
	int *first  = *(int**)a;
	int *second = *(int**)b;
	return first[1] - second[1];
}

int int_pair_desc(const void *a, const void *b){
	return (int_pair_asc(a, b) * -1);
}

int main(){
	char msg[] = "I am a large brown bear who lives in the forest.  My diet consists primarily of honey and spaceships.";
	printf("string: '%s'\n", msg);
	int **counts = count_chars(msg);
	qsort(counts, 256, sizeof(int), int_pair_desc);
	int i;
	for(i = 0; i < 256; i++){
		if(counts[i][1] > 0)
			printf("Rank[%d]: '%c' - %d\n", i+1, counts[i][0], counts[i][1]);
	}
	return 0;
}