修改选择排序算法，通过增加长度对字符串数组进行排序

Question

I've been given an assignment for class and I'm trying to do it but I confused at the wording

Modify the selection sort algorithm to sort an array of strings by increasing length.

Now, this is from the book "Big C++ Late Objects Enhanced etext", 3rd edition, in practice exercises 12.1.

I'm confused at the part "sort an array of strings by increasing length." I don't know what they mean by "by increasing length." I thought that I had to mod the algorithm to where I had to create a variable and make it to where you Console In (or cin>>) to that variable when the programs run but I got a feeling that not what I'm supposed to do.

After looking on some info on my problem along with the comments down below (thanks to the user for them btw) I was able to mod the program to this:

#include <cstdlib>
#include <ctime>
#include <iostream>
#include <stdio.h>
#include <string>

using namespace std;

/**
    Gets the position of the smallest element in an array range.
    @param a the array
    @param from the beginning of the range
    @param to the end of the range
    @return the position of the smallest element in
    the range a[from]...a[to]
*/
int min_position(const char a[], int from, int to)
{
   int min_pos = from;
   for (int i = from + 1; i <= to; i++)
   {
      if (a[i] < a[min_pos]) { min_pos = i; }
   }
   return min_pos;
}

/**
   Swaps two integers.
   @param x the first integer to swap
   @param y the second integer to swap
*/
void swap(int& x, int& y)
{
   int temp = x;
   x = y;
   y = temp;
}

/**
   Sorts a array using the selection sort algorithm
   @param a the array to sort
   @param size the number of elements in a
*/
void selection_sort(const char a[], int size)
{
   int next; // The next position to be set to the minimum

   for (next = 0; next < size - 1; next++)
   {
      // Find the position of the minimum starting at next
      int min_pos = min_position(a, next, size - 1);
      // Swap the next element and the minimum
      swap(a[next], a[min_pos]);
   }
}

/**
   Prints all elements in an array.
   @param a the array to print
   @param size the number of elements in a
*/
void print(const char a[], int size)
{
   for (int i = 0; i < size; i++)
   {
      cout << a[i] << " ";
   }
   cout << endl;
}

int main()
{
  srand(time(0));
   const int SIZE = 6;
   // changed value to Words
   const char * Words[SIZE]={"School" , "To", "Sky" ,"Grade" , "A","Amazing"};



   for(unsigned i = 0; i < SIZE; i++)
   {
      cout<<Words[rand()%SIZE]<<endl;
   }

   print(Words, SIZE);
   selection_sort(Words, SIZE);
   print(Words, SIZE);
   return 0;
}

I made it so that the Words in the "Words" char type will be chosen at random and will continue to do so, sorting out the shortest word to the longest and printing them out. Please note that is a work in progress at the moment.

The problem for me now is that I can't seem to call the functions of print , and selection_sort and I know that just the tip of the iceberg to what needs to be done. I know I can use str.length to sort out the words but now I want to focus on calling the function so any advice is useful.

Answer 1

They probably mean the length of characters in the string. If you use a strings size() or length() method it will return the amount of characters in the string.

If you use this function on every string you will have an array of ints that you can sort in ascending order.