c++ - 为什么我的插入排序函数不会更改我从 int main 传递的数组？

Question

简短版本(使用硬连线输入)

#include <iostream>
#include <string>
#include <vector>

using namespace std;


void insertionSort(string theArray[], int n)
{
  //unsorted = first index of the unsorted region,
  //loc = index of insertion in the sorted region,
  //nextItem = next item in the unsorted region,
  //Initially, sorted region is theArray[0]
  //           unsorted region is theArray [1..n-1].
  //In general, sorted region is theArray[0..unsorted-1],
  //            unsorted region theArray[unsorted.. n-1]

  for(int unsorted = 1; unsorted< n; unsorted++)
  {
    //At this point, theArray[0..unsorted-1] is sorted.
    //Find the right position (loc) in theArray[0..unsorted]
    //for theArray[unsorted], which is the first entry in the
    //unsorted region; shift, if necessary, to make room

    string nextItem = theArray[unsorted];
    int loc = unsorted;

    while( (loc > 0) && (theArray[loc-1] > nextItem) )
    {
      //shift theArray [loc -1] to the right
      theArray[loc] = theArray[loc-1];
    }

    // At this point, theArray[loc] is where nexItem belongs
    theArray[loc] = nextItem; // Insert nextItem into sorted region
    loc--;
  }// end for
}


int main()
{
    vector<string> token;
    int countToken;

    string input= "I,love,doing,nothing,at,all";

    int count =0;
    for(int i=0; i< input.length(); i++)
    {
      if(input[i] == ',')
      count++;
    }



    countToken = count +1; 

    for(int i=0; i< countToken; i++)
    {
      int x= input.find(',');
      token.push_back(input.substr(0,x));
         input = input.substr(x+1);
    }


    cout << endl << "Current String: ";
    for(int i =0; i< countToken; i++)
    {
      cout << token[i] <<"  " ;
    }

    cout << endl;


    string theArray[countToken];

    for(int i =0; i< countToken; i++)
    {
      theArray[i] = token[i];
    }

    insertionSort(theArray, countToken);

    cout << "SORTED: " ;

    for(int i =0; i< countToken; i++)
    {
      cout << theArray[i] << "  ";
    }


    return 0;
}// main

完整版

#include <iostream>
    #include <string>
    #include <vector>

    using namespace std;


    void insertionSort(string theArray[], int n)
    {
      //unsorted = first index of the unsorted region,
      //loc = index of insertion in the sorted region,
      //nextItem = next item in the unsorted region,
      //Initially, sorted region is theArray[0]
      //           unsorted region is theArray [1..n-1].
      //In general, sorted region is theArray[0..unsorted-1],
      //            unsorted region theArray[unsorted.. n-1]

      for(int unsorted = 1; unsorted< n; unsorted++)
      {
        //At this point, theArray[0..unsorted-1] is sorted.
        //Find the right position (loc) in theArray[0..unsorted]
        //for theArray[unsorted], which is the first entry in the
        //unsorted region; shift, if necessary, to make room

        string nextItem = theArray[unsorted];
        int loc = unsorted;

        while( (loc > 0) && (theArray[loc-1] > nextItem) )
        {
          //shift theArray [loc -1] to the right
          theArray[loc] = theArray[loc-1];
        }

        // At this point, theArray[loc] is where nexItem belongs
        theArray[loc] = nextItem; // Insert nextItem into sorted region
        loc--;
      }// end for
    }


    int main()
    {
        vector<string> token;
        int countToken;
        while(1)
        {
          int answer;
          cout << "MENU: " << endl;
          cout << "1. Input String " << endl;
          cout << "2. Sort " << endl;
          cout << "3. Quit " << endl;
          cout << endl;
          cout << "Response: ";
          cin >> answer;
          cin.ignore(1000, 10);

          if( answer == 1) // case 1. Input String
          {

            string input;
            cout << endl << "Default delimiter is ','"<< endl << "Enter String: " ;
            getline(cin, input);

            // find delimiter
            int count =0;
            for(int i=0; i< input.length(); i++)
            {
              if(input[i] == ',')
              count++;
            }

            //cout << "Count: "<< count <<endl;

            //clear previous vector
            token.clear();

            countToken = count +1; 

            for(int i=0; i< countToken; i++)
            {
              int x= input.find(',');
              token.push_back(input.substr(0,x));
              input = input.substr(x+1);
            }

            //cout << "countToken: " << countToken << endl;

            cout << endl << "Current String: ";
            for(int i =0; i< countToken; i++)
            {
              cout << token[i] <<"  " ;
            }

            cout << endl;
          }
          else if(answer == 2) // case 2. Sort
          {
            string theArray[countToken];



            for(int i =0; i< countToken; i++)
            {
              theArray[i] = token[i];
            }

            //cout << "COUNTTOKEN: "<< countToken;
            insertionSort(theArray, countToken);

            cout << "SORTED: " ;

            for(int i =0; i< countToken; i++)
            {
              cout << theArray[i] << "  ";
            }
          }
          else if(answer == 3)
          {

            break;
          }
          else 
          {
          cout << endl << "Invalid input !" << endl << endl;
          }

          cout << endl;
        }// while

        return 0;
    }// main

您好，简单介绍一下我的程序。我要求用户输入一组以'，'作为分隔符的字符串，以便在每次找到'，'时将字符串切掉，并将其插入 vector ，然后将其传递给数组，然后将数组传递给插入排序功能。 (注意:如果字符串中包含任何空格，程序将无法正确切割)

但是，我的插入排序函数似乎并没有改变我正确传递的数组。当我调用该函数时，我的程序甚至崩溃了。我读了一篇文章，它说默认情况下数组是通过引用传递的 因此，我认为函数参数中的“&”符号对于更改 main 中的数组不是必需的。

我希望有人能弄清楚我的程序中缺少什么任何意见将不胜感激

谢谢

Answer 1

主要问题是你没有在循环中改变loc的状态。

while( (loc > 0) && (theArray[loc-1] > nextItem) )
{
  //shift theArray [loc -1] to the right
  theArray[loc] = theArray[loc-1];

  //add this
  loc--; // move to the left so that the shift can go on
}