Thread: can someone help spot the error

hey all, hope you're having a fine weekend all i'm trying to do here is load an array and sort it, but i think my logic doesn't follow. i think the problem is in the sorting. thanks in advance

Code:

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

main()
{
	int const array_size=400;
	int array[array_size], holder;

//seed
	srand(time(0));

//load, sort & display array
	for (int i=0; i<array_size; i++)
	{	array[i]=1+rand() %array_size*2;
		if (array[i]<array[i-1]&&i>0)
		{	holder=array[i];
			array[i]=array[i-1];
			array[i-1]=holder;
		}
		cout<<array[i]<<" ";
	}
	return(0);
}

I'm not that clear on what your trying to accomplish(but everyone else does, right?)

Yeah well it compiles fine on my compiler

What range of "random" numbers are you looking for?

i'm working on a recursive search function, but i can't even get an array loaded with random numbers from 1-twice the size of the array. but the numbers don't seem random. below is what i get, the 1st, 2nd, 3rd, 6th, numbers appear random, but after that they just repeat

51 193 691 691 691 691 691 713 713 713 713 733 733 733 733 733 733 779 779 779 7
79 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 7
79 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 779 7
79 779 779 779 779 797 797 797 797 797 797 797 797 797 797 797 797 797 797 797 7
97 797 797 797 797 797 797 797 797 797 797 797 797 797 797 797 797 797 797 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 7
99 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799 799

you have two problems in your code. First off you only sort only between two elements that are NEXT to each other...what about the stuff before them? For example:

21 20 18 2 //pretend thats your array
20 21 18 2 //after first sort
20 18 21 2 //after second sort
20 18 2 21 //this is after your sort algorithm completes

Your trying to sort in linear time and that is impossible =) You can make a simple sort algorithm with 2 for loops but i'll leave that to you =)

Secondly you are printing out IMMEDIATELY after your sort 2 elements. What you need to do is print out after the sort is completely done. Whats happening is that say 800 is the biggest number and its the second element in your array.

1 800 2 3 4 5 6 7 //your array

Whats going to happen is that you keep printing out array[i]. Well since your making array[i] > array [i-1], through each iteration 800 should be the greatest number thus you will keep printing out 800 after the first 1.

1 800 800 800 800 800 800 800 //your output

Hope that helps you...

-Dennis

thanks prophet, you're my new hero it's not the best but it'll work for now:

Code:

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

main()
{
	int const array_size=400;
	int array[array_size], holder;

//seed
	srand(time(0));

//load
	for (int i=0; i<array_size; i++)
	{	array[i]=1+rand() %array_size*2;
	}
	
//sort
	for (int i=0; i<array_size; i++)
	{	for (int x=0; x<array_size; x++)
		{	if (array[x]<array[x-1] && x!=0)
			{	holder=array[x];
				array[x]=array[x-1];
				array[x-1]=holder;
			}
		}
	}
//display array
	for (int i=0; i<array_size; i++)
	{	cout<<array[i]<<" ";
	}
	return(0);
}

That is the most basic way of sorting but your idea is correct now. Glad I could help =)