Solved

Array comments

Posted on 2006-12-01
4
260 Views
Last Modified: 2010-04-01
I am wondering if you could comment each line of  this code so that I can understand what is doing.

#include <iostream>
using namespace std;

void printArray(int a[], int length){
cout << "[";
 for (int count = 0 ; count < length; count++)
       cout << a[count] << " " ;
cout << "]"<< endl;
}

void enterIntegers(int a[],int length){
 cout << "please enter " << length << " integers" << endl;  
 for (int count = 0 ; count < 5 ; count++)
      cin >> a[count];                                    
printArray(a,length);                                 
}


void swap(int& first, int& second)
{
       int temp = first;
       first = second;
       second = temp;
}

int minimum_from(int a[], int position, int length)
{
       int min_index = position;

       for (int count = position + 1 ; count < length ; count    ++)
               if (a[count] < a[min_index])
                       min_index = count;
               return min_index;
}
         
void selection_sort(int a[], int length)                
{
   for (int count = 0 ; count < length - 1 ; count++)
           swap(a[count],a[minimum_from(a,count,length)]);
}
           

           




int main(){
 int my_array[5];
 enterIntegers(my_array,5);
 selection_sort(my_array,5);
 cout << "The array after sorting it:" << endl;
 printArray(my_array,5);
 char c;cin >> c;
 system ("pause");
 return 0;
}
0
Comment
Question by:mayan1
  • 2
4 Comments
 
LVL 6

Expert Comment

by:xRalf
ID: 18053755
Hi mayan1,
this is implementation of selection sort algoritm. Here is the algoritm http://en.wikipedia.org/wiki/Selection_sort.
Which lines of code don't you undertstand? Have you problem with C++ (syntax, semantics) or algorithm itself?
0
 

Author Comment

by:mayan1
ID: 18054602
Hello xRalf ,
The program works as designed there are no problems with syntax or semantics or the algorithm.  I would like to know when it's sorting, reading, printing, insertion etc.
0
 
LVL 6

Expert Comment

by:xRalf
ID: 18054751
sorting:
for (int count = 0 ; count < length - 1 ; count++)
           swap(a[count],a[minimum_from(a,count,length)]);

I have to go through the whole array from 0 to the end.
You will take the first element and go through the remainder of the array. You will find the minimum element with function minimum_from(...) and
swap it with the first element (if the first element was smaller).
You will take the second element ....
atc.
After the end number of steps the array will be sorted.

reading:
enterIntegers(...) {...}

writing:
printArray(...) {...}

insertion:
The function swap(...) is swaping the first yet unsorted element with the minimum from the remainder, so after each swap we have added one element to the sorted part of array.
0
 
LVL 4

Accepted Solution

by:
Raymun earned 200 total points
ID: 18054932
Hello,

/* swap first with second (obviously) */
void swap(int& first, int& second)  // passed by reference (addresses of first and second), which is why there is no return value
{
       int temp = first;      // next line will overwrite first so store first in temp variable
       first = second;            
       second = temp;
}

/* Return minimum value from a[ position ] to a[ length - 1 ] inclusive */
int minimum_from(int a[], int position, int length)
{
      int min_index = position;

             for (int count = position + 1 ; count < length ; count++) {      // iterate through a[] starting at position + 1 up to length - 1
                     if (a[count] < a[min_index]) {                         // if value at a[count] is < value at a[min_index] then the new minimum value is at a[count]
                  min_index = count;                         // update min_index to reflect new minimum value in a[]
            }
      }
               
      return min_index;
}

/* Will sort from a[0] to a[length] */
void selection_sort(int a[], int length)
{
   for (int count = 0 ; count < length - 1 ; count++)                  // iterate through a[] starting at a[0] up to a[length -1]
           swap(a[count],a[minimum_from(a,count,length)]);            // uses the return value from  minimum_from as the index in a[], then uses the
}                                                      //  value at that index in a[], along with the value at a[count] to send to swap

Hope this helps
-Ray
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
SNMP error No Such Object available on this agent at this OID 3 298
c++ syntax question 9 52
Create a path if not exists 7 89
Why isn't object file created? 6 68
Introduction This article is a continuation of the C/C++ Visual Studio Express debugger series. Part 1 provided a quick start guide in using the debugger. Part 2 focused on additional topics in breakpoints. As your assignments become a little more …
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the b…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will learn how to pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question