C库函数使用集

1 qsort()函数使用

#include  < stdio.h >
#include  < stdlib.h >
typedef  struct  PLANT {
     int  num;
     char  name[ 13 ];
    
}Plant;

int  Mycompare( const   void   * lth, const   void   * rth) // 形参应该是const void*类型
{
    Plant *  lpl = (Plant * )lth;
    Plant *  rpl = (Plant * )rth;
     return  lpl -> num - rpl -> num;
}
int  main( void )
{
     int  i,n;
    Plant plant[ 5 ] = {{ 3 , " wangtian " },{ 1 , " wangshuo " },{ 5 , " wangru " },{ 2 , " wangfang " },{ 4 , " wangxiao " }};
    
     for (i = 0 ;i < 5 ;i ++ )
        printf( " %d\t%s\n " ,plant[i].num,plant[i].name);

    qsort(plant, 5 , sizeof (Plant),Mycompare);

    printf( " \n " );

     for (i = 0 ;i < 5 ;i ++ ) // 输出排好序后的结构体数组
        printf( " %d\t%s\n " ,plant[i].num,plant[i].name);
    printf( " %d\n " , sizeof (Plant));

fflush(stdin); // 刷新缓冲区
   char  q;
  scanf( " %c " , & q);
   return   0 ;
}