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?////////////////////////////////////////////////////////////////////////
//file name: void_pointer 
 c//author: cfjtaishan 
//date: 2013-03-21 
//description: the use of generic function pointer. 
//description: 
//1. Implements integer array to maximum element and an array of strings summary for the biggest string; 
//2. The implementation of the integer array and bubble sort an array of strings; 
////////////////////////////////////////////////////////////////////////

#include  
#include  
#include  
#include  

//this two macros used to compile switch 
# define INTEGE 
# define STRING 


# define LEN 10 
# define DAYS 7 

//declare a generic function pointer 
Typedef int (* pfunc) (const void *, const void *). 
Fswap typedef void (*) (void *, void *). 

//function declaration 
Int compare_intege (const void * a, const void * b); 
Int compare_string (const void * a, const void * b); 
Void swap_for_intege (void * p, void * q); 
Void swap_for_string (void * p, void * q); 
Void * my_max (void * pbufs, const int len, const int size, pfunc CMP); 
Void bubble_sort (void * pbufs, const int len, const int size, pfunc CMP, fswap swap); 
Void initize_arr (int * arr, const int len); 
Void show_arr (const int * arr, const int len); 

Int main (int arg c, char * argv []) 
{
# ifdef INTEGE 
Int arr (LEN), * Max; 
Initize_arr (arr, LEN); 
Printf (" Show the arr the arguments: \ n "); 
Show_arr (arr, LEN); 
Max=(int *) my_max (arr, LEN, sizeof (int), compare_intege); 
Printf (" Max integer is % d \ n ", * Max); 
Bubble_sort (arr, LEN, sizeof (int), compare_intege, swap_for_intege); 
Printf (" After sort: \ n "); 
Show_arr (arr, LEN); 
# endif 

# ifdef STRING 
int i; 
Char * week [only]=
{" Monday ", "Tuesday, Wednesday, Thursday," Friday ", "Saturday", "Sunday"}; 
Char * * max_str=(char * *) my_max (week DAYS, 4, compare_string);//pointer length is 4 
Printf (" -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- \ n "); 
Printf (" Max string is "); 
Puts (* max_str); 
Bubble_sort (week DAYS, 4, compare_string, swap_for_string);//pointer length is 4 
Printf (" After mercifully sort: \ n "); 

For (I=0; i {
Printf (" % s ", week [I]); 
} 
Putchar (" \ n "); 
# endif 

return 0; 
} 

//////////////////////////////////////////////////////////////////////////
//the function name: initize_arr 
//description: initialize array, 
//parameters: 
///in/out arr - integer array first address; 
//[in] len - the largest integer array length; 
//the return value: no, 
//description: 
//////////////////////////////////////////////////////////////////////////
Void initize_arr (int * arr, const int len) 
{
int i; 
Srand (time (NULL)); 

For (I=0; i {
Arr [I]=rand () % 1000;//generate 1000 random Numbers within the 
} 
} 

//////////////////////////////////////////////////////////////////////////
//the function name: show_arr 
//description: print the array element value, 
//parameters: 
//[in] arr - integer array first address; 
//[in] len - the largest integer array length; 
//the return value: no, 
//description: 
//////////////////////////////////////////////////////////////////////////
Void show_arr (const int * arr, const int len) 
{
int i; 

For (I=0; i {
Printf (" % d ", arr [I]); 
} 
Putchar (" \ n "); 
} 

//////////////////////////////////////////////////////////////////////////
//the function name: compare_intege 
//description: compare two integer size, 
//parameters: 
//[in] a - an integer data address; 
//[in] b - another integer data address; 
//the return value: 
If//* a & gt; * b, return the positive integers; 
//* a * b==if it returns 0; 
If//* a & lt; * b, it returns a negative positive integers; 
//description: 
//////////////////////////////////////////////////////////////////////////
Int compare_intege (const void * a, const void * b) 
{
Return * (int *) a - b * (int *); 
} 

//////////////////////////////////////////////////////////////////////////
//the function name: compare_string 
//description: compare two strings, the size of the 
//parameters: 
//[in] a - the address of a string; 
//[in] - another string b address; 
//the return value: 
//and return the same STRCMP. 
//description: 
//////////////////////////////////////////////////////////////////////////
Int compare_string (const void * a, const void * b) 
{
Return STRCMP (*) (char * * a, * (char * *), b); 
} 

//////////////////////////////////////////////////////////////////////////
//the function name: my_max 
//description: for a maximum of the data set, 
//parameters: 
///in/out pbufs - generic data first address; 
//[in] len - the maximum length of the generic data; nullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnullnull