关于标准库函数qsort()的使用

/*e19 编程。使用标准库函数qsort(),对各类数组进行排序。函数原型为：
void qsort((void*)a,int size,int width,int(*fcmp)(const void*,const void*));
(1) 对整数数组排序。要求按每个元素各位数字之和,升序排列。
(12,32,42,51,8,16,51,21,19,9)
(2) 对浮点数组排序。升序排列。
(32.1,456.87,332.67,442.0,98.12,451.79,340.12,54.55,99.87,72.5)
(3) 对字符串数组排序。
(enter,number,size,begin,of,cat,cap,program,certain,a)
*/
#include <iostream>
#include <stdlib.h>
using namespace std;
int cmpint(const void *a,const void *b)
{
return *(int*)a-*(int*)b;
}
int cmpfloat(const void *a,const void *b)
{
return *(double*)a-*(double*)b;
}
int cmpstring(const void *a,const void *b)
{
return strcmp((char*)a,(char*)b);
}
void main()
{
int i[]={12,32,42,51,8,16,51,21,19,9};
double f[]={32.1,456.87,332.67,442.0,98.12,451.79,340.12,54.55,99.87,72.5};
char s[][10]={"enter","number","size","begin","of","cat","cap","program","certain","a"};
qsort(i,10,sizeof(i[0]),cmpint);
qsort(f,10,sizeof(f[0]),cmpfloat);
qsort(s,10,10,cmpstring);
for(int index=0;index<10;index++)
cout<<i[index]<<'/t';
cout<<endl;
for(index=0;index<10;index++)
cout<<f[index]<<'/t';
cout<<endl;
for(index=0;index<10;index++)
cout<<s[index]<<'/t';
cout<<endl;
}