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### Author Topic: C# - Intersection of two arrays - finding the common elements  (Read 1215 times)

#### kathir

• Sr. Member
• Posts: 283
##### C# - Intersection of two arrays - finding the common elements
« on: July 07, 2011, 03:10:00 pm »
Here is the C# source code intersection of two arrays which means finding the common elements between two arrays. The good thing about this coding is it will allocate only the required memory. During the first iterator it will count how many number of unique elements and common elements are available in an array. Then use the count to allocate the memory and fill in the elements in its second iteration.

using System;
using System.Collections.Generic;
using System.Text;

namespace CSApp
{
class Program
{
static int[] Find_Common_Elements(int[] p1, int[] p2)
{
int count = 0;
for (int i = 0; i < p1.Length; i++)
{
for (int j = 0; j < p2.Length; j++)
{
if (p1 == p2[j])
{
count++;
break;
}
}
}

int[] result = new int[count];
count = 0;
for (int i = 0; i < p1.Length; i++)
{
for (int j = 0; j < p2.Length; j++)
{
if (p1 == p2[j])
{
result[count++] = p1;
break;
}
}
}

return result;
}

static int[] BubbleSort(int[] numarray)
{
int max = numarray.Length;
for (int i = 1; i < max; i++)
{
for (int j = 0; j < max - i; j++)
{

if (numarray[j] > numarray[j + 1])
{
int temp = numarray[j];
numarray[j] = numarray[j + 1];
numarray[j + 1] = temp;
}
}
}
return numarray;
}

static int[] Find_Unique_Elements(int[] numarray)
{
BubbleSort(numarray);
int element = numarray[0];
int count = 1;
for (int i = 1; i < numarray.Length; i++)
{
if (element == numarray)
continue;
else
{
element = numarray;
count++;
}
}

int[] result = new int[count];

count = 0;
element = numarray[0];
result[count++] = element;
for (int i = 1; i < numarray.Length; i++)
{
if (element == numarray)
continue;
else
{
element = numarray;
result[count++] = element;
}
}
return result;
}

static void Main(string[] args)
{
int[] array1 = new int[] { 10, 20, 30, 40, 50, 60, 70, 80, 90, 100,
95, 85, 75, 65, 55, 45, 35, 25, 15, 05,
10, 15, 20, 25, 30, 35, 40, 45, 50, 55
};

int[] array2 = new int[] { 15, 25, 35, 45, 55,
12, 22, 32, 43, 52,
15, 25, 35, 45, 55
};

int [] p1 = Find_Unique_Elements(array1);
int [] p2 = Find_Unique_Elements(array2);
int [] result = Find_Common_Elements(array1, array2);

Console.Write("\n\nUnique Sorted Elements in Array1: ");
for(int i = 0; i < p1.Length; i++)
Console.Write(p1 + " ");
Console.Write("\n\nUnique Sorted Elements in Array2: ");
for(int i = 0; i < p2.Length; i++)
Console.Write(p2 + " ");
Console.Write("\n\nCommon (Intersection of) Elements in Array1 and Array2: ");
for(int i = 0; i < result.Length; i++)
Console.Write(result + " ");
Console.WriteLine();
}
}
}

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