void ShellSort(int* data ,int length) {     if( data == NULL || length <= 0 )         return;     int d = length/2;  //步长     while( d )     {         for(int i = 0 ; i < d ; ++i) //根据步长分成组，对每组进行插入排序         {             //插入排序             for(int j = i+d; j <length ; j +=d )             {                 if( data[j] < data[j -d])                 {                     int temp = data[j]; //哨兵                     int k = j-d;                     for(; k >=0&& temp < data[k]; k -=d)                     {                         data[k+d] =data[k];                     }                     data[k+d] =temp;                 }             }         }         d = d/2;     } }