template <class RandomAccessIterator>
 void sort ( RandomAccessIterator first, RandomAccessIterator last );

template <class RandomAccessIterator, class Compare>
 void sort ( RandomAccessIterator first, RandomAccessIterator last, Compare comp );

#include<stdio.h>
#include<algorithm>
#include<string>
using namespace std;

struct product{
 char name[16];
 float price;
};

int array_int[5]={4,1,2,5,3};
char array_char[5]={'a','c','b','e','d'};
double array_double[5]={1.2,2.3,5.2,4.6,3.5};

//结构比较函数（按照结构中的浮点数值进行排序）
bool compare_struct_float(const product &a,const product &b){
 return a.price<b.price;
}
//结构比较函数（按照结构中的字符串进行排序）
bool compare_struct_str(const product &a,const product &b){
 return string(a.name)<string(b.name);
}
//打印函数
void print_int(const int* a,int length){
 printf("升序排序后的int数组:\n");
 for(int i=0; i<length-1; i++)
  printf("%d ",a[i]);
 printf("%d\n",a[length-1]);
}
void print_char(const char* a,int length){
 printf("升序排序后的char数组:\n");
 for(int i=0; i<length-1; i++)
  printf("%c ",a[i]);
 printf("%c\n",a[length-1]);
}
void print_double(const double* a,int length){
 printf("升序排序后的dobule数组:\n");
 for(int i=0; i<length-1; i++)
  printf("%.2f ",a[i]);
 printf("%.2f\n",a[length-1]);
}
void print_struct_array(struct product *array, int length) 
{ 
  for(int i=0; i<length; i++) 
    printf("[ name: %s \t price: $%.2f ]\n", array[i].name, array[i].price); 
  puts("--");
}
void main()
{
 struct product structs[] = {{"mp3 player", 299.0f}, {"plasma tv", 2200.0f}, 
               {"notebook", 1300.0f}, {"smartphone", 499.99f}, 
               {"dvd player", 150.0f}, {"matches", 0.2f }};
 //整数排序
 sort(array_int,array_int+5);
 print_int(array_int,5);
 //字符排序
 sort(array_char,array_char+5);
 print_char(array_char,5);
 //浮点排序
 sort(array_double,array_double+5);
 print_double(array_double,5);
 //结构中浮点排序
 int len = sizeof(structs)/sizeof(struct product);
 sort(structs,structs+len,compare_struct_float);
 printf("按结构中float升序排序后的struct数组:\n");
 print_struct_array(structs, len); 
 //结构中字符串排序
 sort(structs,structs+len,compare_struct_str);
 printf("按结构中字符串升序排序后的struct数组:\n");
 print_struct_array(structs, len); 
}

bool cmp(int a,int b)
{
  return a>b;
}

struct node{
  int a;
  int b;
  double c;
}

bool cmp(node x,node y)
{
   if(x.a!=y.a) return x.a
if(x.b!=y.b) return x.b>y.b;
   return return x.c>y.c;
}

qsort(s[0],n,sizeof(s[0]),cmp);
int cmp(const void *a,const void *b)
{
  return *(int *)a-*(int *)b;
}

int num[100]; 
Sample: 
int cmp ( const void *a , const void *b ) 
{ 
return *(int *)a - *(int *)b; 
} 
qsort(num,100,sizeof(num[0]),cmp); 

char word[100]; 
Sample: 
int cmp( const void *a , const void *b ) 
{ 
return *(char *)a - *(int *)b; 
} 
qsort(word,100,sizeof(word[0]),cmp); 

double in[100]; 
int cmp( const void *a , const void *b ) 
{ 
return *(double *)a > *(double *)b ? 1 : -1; 
} 
qsort(in,100,sizeof(in[0]),cmp)；

struct In 
{ 
double data; 
int other; 
}s[100] 
//按照data的值从小到大将结构体排序,关于结构体内的排序关键数据data的类型可以很多种，参考上面的例子写 
int cmp( const void *a ,const void *b) 
{ 
return ((In *)a)->data - ((In *)b)->data ; 
} 
qsort(s,100,sizeof(s[0]),cmp); 

struct In 
{ 
int x; 
int y; 
}s[100]; 
//按照x从小到大排序，当x相等时按照y从大到小排序 
int cmp( const void *a , const void *b ) 
{ 
struct In *c = (In *)a; 
struct In *d = (In *)b; 
if(c->x != d->x) return c->x - d->x; 
else return d->y - c->y; 
} 
qsort(s,100,sizeof(s[0]),cmp); 

struct In 
{ 
int data; 
char str[100]; 
}s[100]; 
//按照结构体中字符串str的字典顺序排序 
int cmp ( const void *a , const void *b ) 
{ 
return strcmp( ((In *)a)->str , ((In *)b)->str ); 
} 
qsort(s,100,sizeof(s[0]),cmp); 

int cmp(const void *a,const void *b) //重点cmp函数，把除了1点外的所有点，旋转角度排序 
{ 
struct point *c=(point *)a; 
struct point *d=(point *)b; 
if( calc(*c,*d,p[1]) < 0) return 1; 
else if( !calc(*c,*d,p[1]) && dis(c->x,c->y,p[1].x,p[1].y) < dis(d->x,d->y,p[1].x,p[1].y)) //如果在一条直线上，则把远的放在前面 
return 1; 
else return -1; 
}