Sorting an Array

cbrew (7)
I have to sort an array of 10000 elements with bubble sort, select sort, insert sort, and quick sort. And print every 1000th term. Im pretty sure there is something wrong with each sort because both insert and quick sort crash the program and bubble and select dont seem to sort them correctly. here is my code so far.

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#include <iostream>
#include <fstream>

using namespace std;

const int maxs = 10000;

void readem(double a[])
{
	int id;
	ifstream inf;
	inf.open("indata.dat");
	while(!inf.eof())
	{
		for(int i = 0; i <= maxs; i++)
		{
			inf >> a[i];
			i++;
		}
	}
	inf.close();
}
void printem(double a[])
{
	int i;
	ofstream outf;
	outf.open("outdata.dat");
	for(i = 0; i <= maxs; i++)
	{
		switch(i)
		{
			case 1000:
			case 2000:
			case 3000:
			case 4000:
			case 5000:
			case 6000:
			case 7000:
			case 8000:
			case 9000:
			case 10000:
				cout << a[i] << endl;
				break;
		}
	}
}
void bubble(double a[])
{
	int j, l;
	for(l = 0; l <= maxs-1; l++)
	{
		for(j = 0; j >= maxs-1; j++)
		{
			if(a[j] > a[j+1]);
		}
	}
	swap(a[j], a[j+1]);
}
void selection(double a[])
{
	int j, k, small;
	if(maxs > 1)
	{
		for(k = 1; k <= maxs -1; k++)
		{
			small = k;
			for(j = k+1; j <= maxs; j++)
			{
				if(a[j] < a[small]) small = j;
			}
			if(k != small) swap(a[k], a[small]);
		}
	}
}
void insert(double a[])
{
	int j, k, save;
	for(k = maxs -1; k > 1; k++)
	{
		j = k+1;
		save = a[k];
		a[maxs + 1] = save;
		while(save > a[j])
		{
			a[j-1] = a[j];
			j = j + 1;
		}
		a[j-1] = save;
	}
}
void quick(int left, int right)
{
	int j, k;
	double a[maxs];
	if(left < right)
	{
		j = left;
		k = right + 1;
		do
		{
			do j = j + 1; while(a[j] <= a[left]);
			do k = k - 1; while(a[k] >= a[left]);
			if(j < k) swap(a[j], a[k]);
		}
		while(j <= k);
		swap(a[left], a[k]);
		quick(left, k - 1);
		quick(k + 1, right);
	}
}
void main()
{
	double a[maxs + 1];
	int i;
	readem(a);
	for(i = 0; i < 4; i++)
	{
		readem(a);
		switch(i)
		{
			case 0: bubble(a);
					cout << "Bubble Sort" << endl;
					printem(a);
					break;
			case 1: selection(a);
					cout << "Select Sort" << endl;
					printem(a);
					break;
			case 2: insert(a);
					cout << "Insert Sort" << endl;
					printem(a);
					break;
			case 3: quick(0, maxs - 1);
					cout << "Quick Sort" << endl;
					printem(a);
					break;
		}
	}
}
kbw (9488)
You don't seem to keep track of how many items you actually read.

If the number is less than 10001, you could have uninitialised entries with NaN values.

If the number is greater, you will have overwritten memory somewhere is unpredictable effects.
closed account (o1vk4iN6)
There's so much going wrong here...

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void quick(int left, int right)
{
	int j, k;
	double a[maxs]; // what ...
   
        // ...


And some of your algorithms aren't written correctly...

Your bubble sort does absolutely nothing.
Last edited on
cbrew (7)
alright i made a few changes to the code that sorted some of the numbers.

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#include <iostream>
#include <fstream>

using namespace std;

const int maxs = 10000;

void readem(double a[])
{
	int id;
	ifstream inf;
	inf.open("indata.dat");
	while(!inf.eof())
	{
		for(int i = 0; i <= maxs; i++)
		{
			inf >> a[i];
			i++;
		}
	}
	inf.close();
}
void printem(double a[])
{
	int i;
	ofstream outf;
	outf.open("outdatao.dat");
	for(i = 0; i <= maxs; i++)
	{
		switch(i)
		{
			case 1000:
			case 2000:
			case 3000:
			case 4000:
			case 5000:
			case 6000:
			case 7000:
			case 8000:
			case 9000:
			case 10000:
				outf << a[i] << endl;
				break;
		}
	}
}
void bubble(double a[])
{
	int j, l;
	for(l = 0; l <= maxs-1; l++)
	{
		for(j = 0; j <= maxs-1; j++)
		{
			if(a[j] > a[j+1]) swap(a[j], a[j+1]);
		}
	}
}
void selection(double a[])
{
	int j, k, small;
	if(maxs > 1)
	{
		for(k = 1; k <= maxs -1; k++)
		{
			small = k;
			for(j = k+1; j <= maxs; j++)
			{
				if(a[j] < a[small]) small = j;
			}
			if(k != small) swap(a[k], a[small]);
		}
	}
}
void insert(double a[])
{
	int j, k, save;
	for(k = maxs -1; k > 1; k++)
	{
		j = k+1;
		save = a[k];
		a[maxs + 1] = save;
		while(save > a[j])
		{
			a[j-1] = a[j];
			j = j + 1;
		}
		a[j-1] = save;
	}
}
void quick(int left, int right)
{
	int j;
	int k;
	double a[maxs];
	if(left < right)
	{
		j = left;
		k = right + 1;
		do
		{
			do
			{
				j = j + 1;
			}while(a[j] <= a[left]);
			do
			{
				k = k - 1;
			}while(a[k] >= a[left]);
			if(j < k) swap(a[j], a[k]);
		}while(j <= k);
		swap(a[left], a[k]);
		quick(left, k - 1);
		quick(k + 1, right);
	}
}
void main()
{
	double a[maxs + 1];
	int i;
	ofstream outf;
	outf.open("outdatao.dat");
	for(i = 0; i < 4; i++)
	{
		switch(i)
		{
			case 0: readem(a);
					bubble(a);
					outf << "Bubble Sort" << endl;
					printem(a);
					break;
			case 1: readem(a);
					selection(a);
					outf << "Select Sort" << endl;
					printem(a);
					break;
			/*case 2: readem(a);
					insert(a);
					outf << "Insert Sort" << endl;
					printem(a);
					break;
			case 3: readem(a);
					quick(0, maxs - 1);
					outf << "Quick Sort" << endl;
					printem(a);
					break;*/
		}
	}
}


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-9.25596e+061
-7686.42
-5384.97
-3020.2
-614.763
1704.47
4149.78
6478.72
8825.16
liquidfuzz (78)
Hi! I'm not sure of the source of your algorithms, but a good one is Wikipedia. Almost all algorithms you can think of is quasi-coded there. You just need to write them in the language you're tinkering with at the moment, like c++ for instance.
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