利用qsort() 对字符串的内容快速排序

#include "stdafx.h"
/* QSORT.C: This program reads the command-line
 * parameters and uses qsort to sort them. It
 * then displays the sorted arguments.
 */

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

int compare( const void *arg1, const void *arg2 );

void main( int argc, char **argv )
{
 
   char a[255]="1723649/0";
   int k=strlen(a);
  
   qsort((void *)a,(size_t)strlen(a),sizeof(char),compare);
   printf  ("%s",a);
}

int compare( const void *arg1, const void *arg2 )
{
 return -(((char *)arg1)[0]-((char*)arg2)[0]);//降序，这个值取负则为升序
}