尝试使用 qsort,它对我来说运行完美。我在整个程序中使用函数指针和一些我不习惯的其他特性(例如 void 指针)。
但是,我希望元素按降序排列(即与升序相反)。我能做些什么来实现这一目标?
这是代码:
#include <iostream>
#include <cstdlib> // Required for qsort
#include <cstring>
using std::cout;
using std::endl;
int compare_strs( const void *arg1, const void *arg2 );
int compare_ints( const void* arg1, const void* arg2 );
int main()
{
char * shrooms[10] =
{
"Matsutake", "Lobster", "Oyster", "King Boletus",
"Shaggy Mane", "Morel", "Chanterelle", "Calf Brain",
"Pig's Ear", "Chicken of the Woods"
};
int nums[10] = {99, 43, 23, 100, 66, 12, 0, 125, 76, 2};
// The address of the array, number of elements
// the size of each element, the function pointer to
// compare two of the elements
qsort( (void *)shrooms, 10, sizeof( char * ), compare_strs );
qsort( (void *)nums, 10, sizeof( int * ), compare_ints );
// Output sorted lists
for ( int i = 0; i < 10; ++i )
cout << shrooms[i] << endl;
for ( int i = 0; i < 10; ++i )
cout << nums[i] << endl;
return 0;
}
int compare_ints( const void * arg1, const void * arg2 )
{
int return_value = 0;
if ( *(int *)arg1 < *(int *)arg2 )
return_value = -1;
else if ( *(int *)arg1 > *(int *)arg2 )
return_value = 1;
return return_value;
}
int compare_strs( const void * arg1, const void * arg2 )
{
return ( _stricmp( *(char **) arg1, *(char **) arg2 ) );
}
该程序按升序输出(即从小牛脑开始),但我试图让它以 Shaggy Mane 开始(即降序)。任何帮助将非常感激。