Question

我正在生成-100到100之间的随机数＆amp;我试图按升序和降序对＃进行排序，但是当结果只显示第1和第1时显示最后的数字？

// sorting using function pointers.
#include "stdafx.h"
#include <fstream>  // writing data to disk
#include <cstdlib>  // standard general utilities library "# generator"
#include <ctime>   // convert time value to string
#include <iostream>
#include <iomanip> // set precision

using namespace std;

// prototypes
void selectionSort( int [], const int, bool (*)( int, int ) );
void swap( int * const, int * const );   
bool ascending( int, int ); // implements ascending order
bool descending( int, int ); // implements descending order

int _tmain(int argc, _TCHAR* argv[])
{

// Number Generator 
{
    double Final_Avg = 0;
    double Random_Cap = 100;
    double Samples_To_Create = 99;
    srand((unsigned)time(0));
    double rndDbl;
    int rndInt;
    double rndAvg = 0, rndMin = 0, rndMax = 0;
    int counter = 0;
    double temp = 0;
    double dblRanAry[100]; 

    Final_Avg = rndAvg / counter; // final average to display

    double lDbl=0, hDbl=Random_Cap; 
    int lInt = 0, hInt=1;

    double dblRange=(hDbl-lDbl)+1;
    int intRange=(hInt-lInt)+1;



    for(int index=0; index<Samples_To_Create; index++) 
    {
    rndInt = lInt+int(intRange*rand()/(RAND_MAX + 1.0));
    rndDbl = lDbl+double(dblRange*rand()/(RAND_MAX + 1.0));

// random number if statement
    if (rndInt == 0){
        rndDbl = -(rndDbl);

    } //start of Min/Max if statements
    if (rndMin == 0){
        rndMin = rndDbl;
    }
    else if (rndDbl < rndMin){
        rndMin = rndDbl;
    }
    if (rndMax == 0){
        rndMax = rndDbl;
    }
    else if (rndDbl > rndMax){
        rndMax = rndDbl;
    } //end of Min Max if statements

    temp = rndDbl;
    rndAvg += temp;
    dblRanAry[counter] = temp;
    counter++;

    }

   const int arraySize = 100;
   int order; // 1 = ascending, 2 = descending
   int counter1; // array index

// **我认为问题出在这里**

   int a[ arraySize ] = { rndDbl }; 

   cout << "Enter 1 to sort in ascending order,\n" 
      << "Enter 2 to sort in descending order: ";
   cin >> order;
   cout << "\nData items in original order\n";

// output original array
   for ( counter1 = 0; counter1 < arraySize; ++counter1 )
      cout << setw( 4 ) << a[ counter1 ];

// sort array in ascending order; pass function ascending 
// as an argument to specify ascending sorting order
   if ( order == 1 ) 
   {
      selectionSort( a, arraySize, ascending );
      cout << "\nData items in ascending order\n";
   } // end if

     // sort array in descending order; pass function descending
     // as an argument to specify descending sorting order
   else 
   {
      selectionSort( a, arraySize, descending );
      cout << "\nData items in descending order\n";
   } // end else part of if...else

   // output sorted array
   for ( counter1 = 0; counter1 < arraySize; ++counter1 )
      cout << setw( 4 ) << a[ counter1 ];

   cout << endl;
   system("pause");
} 
 } // end main

// multipurpose selection sort; the parameter compare is a pointer to
// the comparison function that determines the sorting order
void selectionSort( int work[], const int size,
                    bool (*compare)( int, int ) )
{
   int smallestOrLargest; // index of smallest (or largest) element

   // loop over size - 1 elements
   for ( int i = 0; i < size - 1; ++i )
   {
      smallestOrLargest = i; // first index of remaining vector

      // loop to find index of smallest (or largest) element
      for ( int index = i + 1; index < size; ++index )
         if ( !(*compare)( work[ smallestOrLargest ], work[ index ] ) )
            smallestOrLargest = index;

      swap( &work[ smallestOrLargest ], &work[ i ] );
   } // end if
} // end function selectionSort

// swap values at memory locations to which 
// element1Ptr and element2Ptr point
void swap( int * const element1Ptr, int * const element2Ptr )
{
   int hold = *element1Ptr;
   *element1Ptr = *element2Ptr;
   *element2Ptr = hold;
} // end function swap

// determine whether element a is less than 
// element b for an ascending order sort
bool ascending( int a, int b )
{
   return a < b; // returns true if a is less than b
} // end function ascending

// determine whether element a is greater than 
// element b for a descending order sort
bool descending( int a, int b )
{
   return a > b; // returns true if a is greater than b
} // end function descending

Answer 1

是的，问题确实存在。

   int a[ arraySize ] = { rndDbl };

将使用a中的值初始化double rndDbl;中的第一个元素，同时需要复制整个数组。

   int a[ arraySize ];
   for ( counter1 = 0; counter1 < arraySize; ++counter1 )
     a[ counter1 ] = dblRanAry[counter1];

直到我没有看到创建数组持有双精度的意义，只是在数据填充后立即将它们转换为int。为什么不直接用a填充数据。

排序程序仅显示1st＆amp;最后一个号码

1 个答案: